Other than what Mylenium suggests, there isn't a whole lot else we can do. It is a very unwise thing to jump into using AE without introducing yourself to the basics, because the application contains too many ways to foil the uninitiated. Furthermore, since you don't know the arcane AE lingo, there are also translation issues to deal with.
Almost NO ONE successfully learns AE intuitively. Those who are successful have last names that begin with the letters "ein" and end with "stein". Almost EVERYONE has to start with the basics. Here is a very good introduction to the basics.
Fight the temptation to jump right into AE. You do so at your peril.
You could also be rendering to the default uncompressed render settings. Uncompressed video will not play back reliably. One of the symptoms is audio out of sync. Another is stuttering playback.