Thanks for the compliment about www.carnytown.com. The background individual color tab changes are done by adding css to the advanced area of your appearance area.
Jen gave me the code to do it. Since I am not much of a teacher she might have to give you the details. Suggest you drop her a line.
I hope you find what you are looking for. It would be nice if Ning would develop a comment box for the main page. Maybe this would be a great topic discussion to start on creators.ning.com I am not sure if anyone has this topic of discussion on the Ning Creators site.