If you're just starting out I would leave Android out of it for now. Get it going in a Java
desktop app, and once you have the mechanics of hiding/recovering working, then embed it in an Android app. It's easier to get going with a desktop app than messing around with Android emulators/devices.
I would advise to use still images, not music or video which are harder to manipulate. For a school project, that should be perfectly acceptable.
And I bet you'll find a lot more results by searching for "java steganography" than for "android steganography" :-)