After Effects - The effect that can save sites

Ok, I have downloaded the Demo for AE.

What I am trying to create, is some kind of ae texture similar to that of this site, when you click on a button.
Ex: Click on services and then check out what happends behind the logo at the top left!

Anyway, what I am looking for is a push in the right direction. I have been to all of the AE links suggested by this site and Forum, but none of then would help me het a background texture.

So any tutorials or links would be awesome!