not a bad first sig at all....if you cut out that render yourself...you did a pretty nice job. the BG is a little plain, but as you learn to do more you will figure all of that out.
a border is really important as was already stated.
one way to kind of cheat until you learn some tricks is to make the team logo take up most of the background and blend it in a bit (lowering its opacity..changing its color, overlaying it etc). its an easy way to make a sig feel more complete and not as empty.
keep em comin and show us your progress