Lots of interest in 'shooting the Moon'! 
You need to learn the Looney 11 Rule. Set aperture to f/11 and shutter speed to the [reciprocal of the] ISO. <---Looney 11 Rule
Next you need to learn how to bracket because this like most photography stuff is just a starting point. Remember it is daytime on the Moon. Even if it is night time where you are.
Do you have the fixed aperture mirror lens or the adjustable aperture refractive lens? If the latter use the Looney Rule as is for starters. If your lens is fixed f8, adjust it by one stop brighter. Example, f11, SS100 and ISO 100 change it to f8, SS 200 and ISO 100.
Of course you need a good tripod.
Actually this lens which is made and branded by several different companies, does a reasonable job with IQ. Essentially similar to the average kit lens. It can be helped even more by a good post editor. BTW, a post editor is essential for good Moon shots.
I'm noticing a lot more interest in astrophotography and lunar photography these days.
I'm aware of two different 500mm lenses with the Bower name on them.
One is basically an acrhomatic lens (like a achromatic refracting telescope) and it does have an aperture adjustment. It's widest aperture is f/8.
The other is a "mirror lens" (basically a Schmidt-Cassegrain design) and it's f/6.3 and it does NOT have an adjustable aperture (it's permanently fixed at f/6.3.)
If you have the f/6.3 "mirror lens" version then that's 1.7 stops brighter than f/11 so you'd need to increase you shutter speed by 1.7 times... instead of using ISO 100 and 1/100th you would use ISO 100 and 1/320th.
If you are using the refractor version of the lens then just stop down to f/11 on the aperture ring and shoot ISO 100 and 1/100th.
If the moon is high in the sky (not just barely rising or setting on the horizon) then you'll nail the exposure. If the moon is at the horizon then it'll likely be dimmer (and orange) so you'll need a longer exposure.
The moon is consistently lit by sunlight. While you could shoot it as a "Sunny 16" rule exposure (the exposure rule for shooting a subject outdoors in bright mid-day sun) what's going against the moon is that it does not have a very reflective surface. Only about 1/8th of the light that hits the moon is reflected. It has the same amount of surface reflectivity (astronomers call this "surface albedo" or just "albedo") as a worn asphalt road. For that reason, the extra stop of light (using f/11 instead of f/16) helps brighten it up so it doesn't seem so dim.
The moon will look better in 1st quarter or 3rd quarter phases (but 3rd quarter moons rise a few hours before sunrise whereas 1st quarter moons don't set until a few hours after dark... so you don't have to set your alarm clock to wake up extra early like you would to shoot a 3rd quarter moon.) This is because the sun is lighting the moon from the side and means the mountains and crater walls cast shadows that really help give the lunar surface a 3-dimensional look (the moon looks like a flat 2d disk if you shoot it at the full moon.)
500mm isn't a lot of focal length to get a detailed shot of the moon -- especially using a full frame sensor camera like your 6D.
Here's an image I took (and posted) quite a while ago, and this image DOES use the "Loony 11" rule. But it's shot using an APS-C size sensor camera (in my case it's a Canon EOS 60Da camera -- my astrophotography camera) and the camera is attached to a TeleVue NP101is quad-element apochromatic refractor telescope (540mm f/5.4 telescope) along with a TeleVue 2x powermate (focal length multiplier) which effectively gives me 1080mm focal length at f/10.8 (close enough to f/11).
The moon is only 1/2º from edge to edge (that's the "angular dimension" -- btw, the moon has an elliptical orbit so the orbital distance varies by about 10% during the lunar month -- but that only changes it's apparent size by a few arc-minutes -- it's still always going to be very close to 1/2º wide.)
With your 500mm lens on a full-frame camera body, the "angular" dimension of your field of view is 4.1º x 2.7º (you can use an angular field of view calculator like this one to determine those values: http://www.tawbaware.com/maxlyons/calc.htm ). That means you would be able to easily fit 5 moon diameters in the vertical dimension (the short dimension) and just over 8 moon widths in the horizontal direction. This wont be a particularly large moon in the image.
If you want a larger moon then you'll need more focal length -- which is why I use a telescope.
Incidentally... there's a story behind the image above. I am involved in a fairly large astronomy club and I'm rather passionate about astronomy, astrophotography, I am also a planetarium operator/presenter, etc. So one day at one of our public observing events, I had a couple that was interested in learning how to photograph the moon. I *happened* to have my camera with me but it wasn't attached to the telescope because I was not planning to do any astrophotography that night.
But since they were looking for advice, I explained the rule and how to know how to set the ideal exposure. With that, I explained the focal ratio of the telesocope was f/5.4 and that I was going to attach the 2x focal length multiplier (bringing the focal ratio to f/10.8 -- close enough to f/11) and therefore we'd just set the camera to take a manual exposure, set the ISO to 100 and set the shutter speed to 1/100th sec. We attached the camera to the telescope, focused, and took ONLY ONE shot. This is that shot.
The point is... if you follow the rule when the moon is high in the sky (not at the horizon where atmosphere will dim it somewhat), you WILL nail the exposure.
As a passionate amateur astronomer, I can generally always tell you where the moon will be or when it will rise & set.
A 1st quarter moon rises at mid-day and sets at mid-night (varying by about an hour a day depending on how many days it is "before" or "after" the 1st quarter).
A full-moon rises at sunset and sets at sunrise. (again... varying by about an hour per day).
A 3rd quarter moon rises around mid-night and sets around mid-day.
A "new" moon rises at and sets with the sun (the moon will appear very near the sun in the sky -- although we are seeing the non-lit side of it so it is very difficult to see.)
Just like the Sun, the stars, and everything else in the sky... the moon "rises" in the east and sets in the west.
If you're framing up the moon by itself, then it's nice to let it climb higher in the sky -- don't shoot it until it's at least 30º above the horizon. The atmosphere will cause distortion -- specifically an effect called "atmospheric dispersion". Any object near the horizon will be distorted by this effect. You would notice a photo of the full moon would have a very slight blue-fringe on one edge and a slight red-fringe on the other edge. This actually causes a blurring of the whole surface and you'll get a sharper image if you fix that. To fix, you'll need a more powerful photo editor like Photoshop. Down in the right where you normally see the layers, click the tab to switch to "channels" then pick one specific channel (such as "red"), click the "move" tool (upper left margin) and then use the arrow keys on your keyboard to move the channel by just 1 pixel, then flip back to "all" channels and see if that was enough to line it back up (unfortunately I don't know of a way to display all channels but move just one or it would be easier to adjust until it's converged.) I usually adjust the "red" channel to bring it in line with the "green" channel and likewise also adjust the "blue" channel to bring it in line with the "green" channel. This will result in a sharper image of the moon by countering the effect of atmospheric dispersion.
If you're shooting a landscape with the full moon in the shot, then it's best to shoot it near moon-rise AND it's also best to shoot it at least ONE DAY BEFORE the day of the full moon (the moon will still look "full") This is because as the moon rises, the basckground sky will still be dusky blue and you'll be able to see the foreground (it wont be dark.)
There are two apps (that work on smartphones) that you might want to have to help with planning.
One is "The Photographers Ephemeris" and the other is called "Sun Surveyor" (which also does the moon).
Both work similarly in that you set the date & time when you'd like to shoot. They will tell you the position where the sun and moon will be in the sky AND they'll overlay that onto a Google Map.
Suppose I want a photo fo the moon rising over a particular mountain peak. I can use the tool to show the point where the moon will rise (and the path it will take across the sky). I can point a spot on the map and it'll show me the relative angle to the moon or sun. I can then MOVE that spot on the map until that line passes over that mountain that I want in my shot... and basically you are using the tool to show you where you'll need to stand and wait for the moonrise if you want the moon to be framed exactly where you want it for your shot.
I use Sun Surveyor on my iPhone... but only because "The Photographer's Emphemeris" was only available as a desktop app (Java client) and they didn't have a mobile phone version (even though they were first). So I ended up going with Sun Surveyor because they were "the only thing that did this" at the time. Now the folks who wrote "The Photographer's Ephemeris" have ported it to mobile phones and smart devices (iPads, etc.)
Here's a sample...
I live in Dearborn, MI -- the hometown of Henry Ford. At the Henry Ford Estate (Henry Ford called it "Fair Lane" -- sound familiar?) Henry Ford had a meadow cut through the trees to produce a view of the sunset and on the day of the summer solstice, the sun would set exactly between the trees as viewed from his back patio.
So here's the image of the software (Sun Surveyor running on my iPad) set to that date. I have the time set to 8:54pm and at this time the sun is still 2º above the horizon (it doesn't set until 9:13pm on this day). But I can see the exact position of the sun from the back-patio of the estate.
See the image here:
Using this, I was able to plan to get this shot:
My screen shot is from the "Sun Surveyor" app running on my iPad, but "The Photographer's Ephemeris" is the first program I knew of that did this (they just didn't have a mobile version at the time - but they do now) and they do pretty much the same thing.
Either is ideal to help you figure out "when" and "where" you need to stand if you want to get the moon (or sun) at a specific spot in your images relatively to a foreground landscape feature on Earth.
"Ephemeris" is what astronomers call the orbital data that we use to calculate the position of solar system objects (all objects in orbit have "ephemeris" data which determines the shape, angles, etc. of the object in orbit around another body.)
The folks who write "The Photographer's Ephemeris" also have an app named "The Photographer's Transit". This app works similarly to "The Photographer's Ephemeris" but it's intended for owners of interchangle lens cameras (like DSLRs) and it calculates the size of the field of view based on your camera and lens. That means that rather than just drawing a line on a map showing where the sun or moon will be from your position, it draws a triangle shaded region on the map showing you everything that will be within the field of view of your camera based on where you are standing and the camera and lens you are using to take the shot. In other words it helps you plan your composition.
