Everytime I try to take a group photo, the center of the image is in focus only, but the edges become like motion blurred!!
Also, it doesn't focus on the right place.
Is it my lens problem or my technique?
In your picture, the people at each end are slightly farther from the focal plane than those in the middle. So if the lens is focused on the middle, the ends will be slightly out of focus. This won't matter, as long as the ends are within the depth of field of the lens. But if you're using a wide aperture, the depth of field will be shorter. And lenses tend to focus better in the middle anyway; so if you're using a cheap lens, the loss of focus is apt to be more noticeable.
Focusing in the right place depends on making sure the camera uses the right focus point. In automatic modes the camera tries to pick the right one, but doesn't always succeed. So you're likely to get better results if you choose the focus point yourself rather than relying on the camera to do it.
I think the entire image is soft, not just the outer edges.
When the entire image is soft, that usually points to poor technique coming into play. The lighting is not the best, which suggests a slow shutter speed. I would be curious to know the exposure settings, as well as the effective focal length of the camera and lens combo.
The quality of the lens cannot be ruled out, either. A low quality lens can also cause an entire photo to look soft. I do not think this is a depth of field problem.
I agree with everyone else, offering a bit more info within the forums would narrow down what this issue is. but I have a feeling this issue is more about the lens you're using or the lens is not suited for the distance you've selected. A ggod way to help one figure out what lens is best suited for any particular sisuation would be to scan through the YouTube videos made by Chris Frost
Again not knowing what lens you're using I couldn't nail down a specific video.
From my view of the image it looks to me like the lens has lost alignment and the right side is badly defocused. Is this consistent across other images you have taken? Has the lens been impcated at some stage?
If that is the case you have two options depending upon the value of the lens - send it in to be re-aligned or if it is a cheaper unit, get something else.
This is a lens issue.
The EXIF data shows this was a Tamron 18-200mm lens at 22mm.
My guess is that the lens is damaged. I'm noticing background (look at the decorative wood treatment on the building facade in the left side of the image) is focused better than the right.
To me... this looks like a lens element (or two) is askew in the lens barrel. Has the lens been dropped or taken a hard hit?
"Super Zoom" lenses, such as this one, aren't idea in general. They trade convenience for quality. But this lens should be doing much better than this. I think you have a damaged lens.