Forum:How do I change the main menu image?

Hello! I'm new here, and I run a Wiki, which I'd rather not disclose the name of (It's a secret currently ;)) but, like where it has the "COMMUNITY CENTRAL" image logo above the main menu, I want to change that image on my wiki- can someone help me please?
 * See Help:Logo. -- 20:34, June 28, 2010 (UTC)