It isn't necessarily supposed to be space, with stars and everything. I though of it as more of a moon with a more abstract background.
Thanks for the comments. As I said, this is my first in a while, so I still have to get back into the swing of things.
I used an image like this and cut out circle. All of the lighting on the bottom was created by me. Here's the colored version.
I really appreciate all of the comments. For some reason, the colored version didn't work. Here is it again, for everyone who said it needed color: