Background colour/image?, in css xD

[spocks_ears]

For some odd reason, whenever I put a background colour or image thingy into css, it just stays white. It works fine when I do it in the normal html file, but that defeats the purpose of css...
Anyways. I know the code is correct cos I've checked on loads of sites...html dog, here, lissa explains..another one which I forget...but it refuses to work.
Any ideas?

[desdemona]

First of all, you'll need to post the actual code since the fact that it's not working indicates that something is not correct. A link to the site with the problem would also be helpful. Are you using external or embedded stylesheet or inline styles?

Secondly, I'd appriciate if you took the time to read the welcome post and welcome section of this board and posted an introduction in the appropriate section. That's the least you can do if you expect us to help you out.