Many of the classes and ids you will want to change are not yet listed in your stylesheet; they are provided in the PHP code in case someone wants to use them. You can add to the stylesheet any you don't find there already.
The best way for you to find which selectors to style is to install Firefox and its Web Developer extension. The Information > Display Element Information button will give all sorts of useful info for any element you click on, including the class/id.
If you want to change colors for a whole group of elements, find the highest container or "ancestor" that includes just them; or else the class tag that they all have in common.
If you want to change just one element, find its id, which will be unique.
(Class tags are identified by a . at the beginning; id tags begin with a #.)



