Changing color to background image?

Hello there. I need to appeal to the experts here. I'm soooo inexperienced with style sheets and I don't want to mess up my new site. I'm using the "Mostly Grey" template for my store and want to change the dark grey color in the category/box headings to an image which will coordinate with my main pages. How do I do that? Here's what I have so far:
http://fantasyrealmcreations.com/store/

The gif I want to use is in my template image file. I downloaded the template from here:
http://(sorry, site offline)/136/index.php?main_page=index&template_dir=mostlygrey

Thanks!
-Michelle

Something Like:

#navCatTabsWrapper {
	margin: 0em;
	background-color: #abbbd3;
	background-image: url(../images/your_image.gif);
	padding: 0.5em 0.2em;
	font-weight: bold;
	color: #ffffff;
	height: 1%;
	}

If it is a tile add a repeat-x