Hey i know how to fix the lip-syncing.
It's really simple, when you put the sound clip in flash, make sure you set it to "stream" in the movie. That way you can actually listen to each sound as you go frame-by-frame. It makes syncing much easier.
As for the movie, its pretty decent considering you're only 12. As long as you keep working with flash you'll get better and better so keep it up!