If you save it as a .gif file, you should lose the white background. Currently, you have it saved as a .jpg .
haha dude, try again with cutting the stuff around the render out.Make sure the bg layer is deleted and make sure u made it transperent and also save it as a gif.U might want to try matte!
or u can just make a regular sig, then just extend the canvas size... i find it easier that way, no extra work, and make sure the render ( pop-out ) fits within it.... In your sig, not only do you have the area above the sig extended, but all around the sig. Then all u gotta do is save it as a .gif
nice to see u got it working, looks alright. Just the render doesnt looks so good, not great quality. OVerall i say for ur first pop^ 7/10