I'm going to show you how to make your system truly your own. I'll show you how to change your background, your colors, your fonts, and anything else you need to create a desktop as individual as you are.
Read the chapter from “Moving to Ubuntu”
As I've already mentioned, working in the Linux world is working in a multiuser world. This means that everyone who uses your computer can have his or her own unique environment. Any changes you make to your desktop while you are logged in as yourself will have no effect on little Sarah when she logs in to play her video games. If she happens to delete all the icons on her desktop or change everything to a garish purple and pink, it won't affect you, either.