I'm still pretty green to after effects, and was looking to add texture to parts of an animation. I'm not really sure how to describe it, but I'm going for the same effect they used in the earlier south parks, like they did on the road and some of the clothes in the screen cap http://bloggingexperiment.com/wp-content/uploads/2007/12/southpark.jpg
sorry, hope this makes sense
Using Stan's hat as an example. Take the hat and texture and drop them into a new composition, make the hat the top most layer. Now take the texture and change the track matte to alpha matte. Last, take this entire comp and move it into your final composition.
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.