Changine the background behind the logo?

I am using the classic template and I already rewritten my logo.gif with the original logo.gif. I want to change the white color background with an image background but I dont know where in the stylesheet do you do this? I dont see anything that says header bg in the code...

Does anyone have a chart of what the css coding means? I know there was a chart on zen somewhere, but now I cant find it.

thanks in advance!

I would like to add one more thing..

I am using the newest version of zen and the classic template with the stylesheet.css ...

I dont know what I did, but somehow the blue original logo (which I believe is the header_bg) behind the logo.gif is back... but i dont see the code in the stylesheet for the header _bg.... I do see the code in the stylesheet_original.css but I am not using this one.. How do I get rid of it?

Help!

is this at a url we can see or on local development machine?

sorry, here is the url http://cherylsjewelry-n-giftnook.com/zencart/

looks go to me.