There is no fixing this sig, just throw it away. I would you rather not even use a render for that sig. Go to planetrenders.net, sign up, and get better quality renders.
Also the text is a poor font and the gradient makes the left side of the bottom text unreadable. Also the colors are decent because they aren't totally clashy on the first. As far as the second.... WTF is up with the stars? Red Stars + Green Elite + Green and Black BG = O_o<No
Next person to say that this signature is trash gets flamed by yours truly, with a red ribbon on top, and a cute little stamp that says "From me to you."
This thread here has a lot of sites that can help you out.
I also recommend downloading some brushes, and practicing with them, Deviant Art is a good place for brushes.