I'm new, and this is the first time I've felt brave enough to show anyone something I've done.  Is it any good?  Is there any hope for me?

This is quite nice. As Souly implied, you should either make the background non-transparent, or skip the outside anti-aliasing. I also think there's something a little funny about the shading on the elbow -- a little too much shadow there, I think. Other than that, I don't see anything wrong with it -- keep up the good work, and keep posting!