Not bad.
If that's really your first attempt that's actually not bad, especially when compared to the things many other people submit as their first games/movies.
Of course, it's a rather simple game concept, but it's executed well and the animation looks fluid. There's just two things that bother me a bit:
1) The sounds seem a bit loud, maybe you could turn them down a tad. On a slightly different note, the sound that is made by hitting the walls, floor or the ball itself seem to be coming a little bit too late. But maybe that's my machine's fault, I don't know.
2) Maybe it would be better if you didn't have to click to kick the ball, but rather just have the ball jump on contact with the cursor. This is just my opinion, though.
Anyway, keep up the good work.