Agreed, you were a tad vague on what exactly you want.
What I assume you want is a simple "Toast" message. Though you could also be asking for a "Dialog". There's plenty of information on both of these if you do a simple Google search, but if you could at least clarify your needs a little we could send you in the right direction.EDIT ::
I didn't remember it earlier, but one of the many Android tutorial sites I have bookmarked has a tutorial that should have you covered regardless of what kind of "balloon notification" you want.http://mobile.tutsplus.com/tutorials/an ... sdk-alert/