Wordpress Themes - WP Forum at BFA - How do I add a NEW css item?

OK, I've used the "add css" area to add additional properties to EXISTING css stuff, but how do I add a completely new css styling option?

I have a site I'm trying to create a Restaurant menu for, using css to style it. I've found sample css to start with, but I can't figure out how to tell wordpress that this is a new thing I'd like to add...

For example, when I'm setting up the menu, I have no way of "tagging" the different text to be something other than "body" text? In TinyMCE, there are "styles" that can be applied, but the "menu" options I'm trying to add isn't available. How do I add this new css?

This is the css I found that I'm trying to start from:

Code:

div#menu {-x-system-font:none;font-family:"Trebuchet MS",Arial,sans-serif;font-size:90%;font-size-adjust:none;font-stretch:normal;font-style:normal;font-variant:normal;font-weight:normal;line-height:normal;margin:0 auto;text-align:left;width:550px;}

h2 {color:#008C00;font-size:250%;margin:1em auto 0.3em;text-align:center;}

dl {background:transparent url(dot.gif) repeat-x scroll 0 1.2em;margin:0 0 1em;overflow:auto;width:100%;}

dt, dd.price {background:#FFFFFF none repeat scroll 0 0;font-size:130%;font-weight:bold;}

dt {color:#F70000;float:left;padding-right:3px;}

dd {margin:0;}

dd.price {color:#AAAAAA;float:right;padding-left:3px;}

dd.ingredients {-x-system-font:none;color:#555555;float:left;font-family:Georgia,Times,sans-serif;font-size:100%;font-size-adjust:none;font-stretch:normal;font-style:italic;font-variant:normal;font-weight:normal;line-height:normal;padding:3px 0;width:100%;}