The best advice that I can give you is to start off with a smaller area...(probably 500x120 at max) You won't have as much space to fill up and the sig will definately look more appealing.
Well in that case, you should see the Opactity/Fill settings in the Layers window...So simply change those levels for any given layer to change its transparency...
I'm not sure what you mean by "fade" though...
edit: sig under construction
I tried putting one of the more creative borders on there, but when I saved it, a lot of the quality was lost ...
Well, that's the best that I could come up with in the half an hour I had to work on it.