How do I do this?

I want to have photos on the wall but i want to be able to go in front of them, so is there a way to put a picture over some of a video?

You have video of a person walking by a wall.
You want to composite framed photographed on that wall.
The person walks in front of the pictures, which are in front of the wall.

Is that correct?

You'd do that in Motion, not in FCP X. That's a complex composite and matte job. You'll have to put the photos on top of the video clip, obviously, and then have a matte moving with the person walking, that makes the photos invisible when the matte passes over them. Lots of keyframing, as a person walking is a dynamically changing form, not a static shape moving.

Could be some work depending on how the person moves, and how long the clip is, but could be done pretty easily. Just time consuming.

Thanks for the help, I think ill purchase motion 5 tomorrow since its rather cheap.