How to align camera and projector?


Hey Friends,
I’m a beginner and no expert coder what so ever.
I’m trying to use a camera (PS3 eye) to do some motion tracking / frame differencing and than project it over the same surface i’m tracking.
I want to be able to project over a screen and track if someone is moving in the projected area and basically generate graphics using the different openCV tools …

my problem at the moment is that the camera frame is different and I need to crop it and than resize it to match the projected surface area.

any ideas where to start ? - at the moment i’m just trying to physically align them but if i’ll be able to crop the screen in the camera and to project it I should make it work.
Thanks again