Watch some basic tutorials. Seriously.
You can also spend a few days searching for "creating custom screen graphics for movies." Try youtube but you wil lfind better stuff on vimeo. Many fo the motiongraphics forums have discusssion areas where artists will share their methods. Lopok carefully for behind the scenes features and docos created by the artists.
However, After Effects is only where the animation happens. You design and previsualize your effects in other applications. Well, there are some fabulous presets you can purchase but, of course, they are relatively expensive. Once your familiarity with AE goes beyond the most basic stuff, you wil appreciate why presets and effects packages cost what they do.