Well, I actually made an item to aide users such as yourself
. Check out this link
http://www.daniel15.com/index.php?ind=downloads&op=entry_view&iden=5 for my name color/style change item.
But since you asked, I will explain a little CSS.
CSS, as well as many other languages, use hex codes for their colors. It's rather simple, you input values for each RGB color. RRGGBB, 990000, 99 Red, 00 Green, 00 Blue. The values go up to FF.
The syntax for CSS is rather simple as well.
selector { property:value }
For use with the Display Name CSS item, you do not need to worry about the selector. What you need is the property and a value for it. In the case of adding colors, "color" will be your property and the hex code for the color you want will be the value.
Red:
color:#FF0000