Personalization has changed a bit in windows 7 from vista but it works basically the same way. The main screen gives you access to new themes that are available. At the bottom of the page you have access to change the desktop background, window color, sounds and screensaver. On the left you have access to desktop icons, mouse pointers and your account picture, at the bottom on the left you have display.
If you click on desktop background you will open a window that allows you to change the background, if you wish to choose a picture of your own rather than one of windows default pictures then click the browse button by picture location.
If you click on window color you get a window that is basically the same as vista's.
If you click advanced appearance settings you get the classic change settings window.
Next lets look at what happens when you click on display from main personalization window. Next