I’m not sure what remote you have, but if it’s a Canon optical remote then you need to set it up through the ‘Drive’ function. On the Rebels it’s usually selected on the back panel on those four buttons in a circle shape. Hit the left one and then scroll right a couple spots to the one that has an icon of a remote. Then just point the remote at the front of the camera and activate.
Make sure to turn it back to normal or continuous drive afterwards, otherwise there’s a ten second delay when you push the shutter. I use a remote a lot, and often forget, not a big deal but it’s usually annoying.
If it’s a wired remote just plug it into the port on the side and push the remote to trigger the shutter.
