Creating a new style

I like the look of Litejazz, and would like to be able to create a "style" of Litejazz which would fit my own requirements (notably for colour).
Can you let me know what files (css etc) I would have to change, and how they would have to be named, so that I could create a new style that would appear in the dropdown list in the Litejazz theme configuration page?
Many thanks!