I have a very simple shot I need to compose. It's a locked off shot of a screen with four green Squares in the corners and a green Plus in the middle I'm just inserting an image over it. Is there an easy way to just take my image and have it paste into those four corners? It should be easy, I just haven't found the effect or seen any tutorials online. Thanks.

Sounds like you want corner pinning -- which is a function of the 3D Warp Effect under Blend in the effects palette.  Just place each corner of your image where you want it to go on the screen.  With a lockdown shot with no tracking it should be very simple.