gradient backgrounds?

(disclaimer: I hate web design)

I got custom buttons an icons working (any good source for more? prefer free and in a collection format)

But I have seen some samples of control pages with gradient backgrounds. how can I enable/create that? I can make a pic of it, but the dynamic aspect (different size browser windows) aspect eludes me.

[matt (support)]

For mine I have just have a few different versions of the image at different heights. Not ideal, but it works.