I'm trying to create a sparkle effect in which i have a small video on top of the main video. The small video has a circular matte so it's in the circular shape, and I want the border to have a sparkle effect.. as if it is a star or something. Can someone point me to the proper effect or a tutorial?
Not sure what you want here. Do you have a screenshot or link to an example?
There are tens of thousands of tutorials for After Effects, many are rubbish, but you get what you pay for. The problem is finding something that is a precise discrition that you can understand of exactly what you think you want. You can look up sparkle and you will eventually find out that what you really are looking for are particle tutorials. Then you may discover particles are really complex. Really. Isn't there an easier way?
CC Particle Systems II, under Simulations, will create sparkle particles from within a shape.
Video CoPilot --> The Ring tutorial