If you want to make a very simple sky, with no clouds and stuff like that, you can do as helm did with his background, (and I do not mean the stuff around his head)

F*, I can´t get that f*-ing link thing working.anyway here is the adress, just zoom in and watch the two colours blending together in the back.

now you don´t have to do it so big, but you know what I mean...

http://www.pixeljoint.com/pixelart/6661.htm

Cool, I actally like it better upside down by some reason .

If I vere you I would make a more dynamic background, not just plain blue. maby some clouds, or a sun, or some birds, or maby just a lighter blue colour blendibg in with a darker.

And welcome to pixeljoint.