For newbie users, you may having difficulties to change the default theme of your Fedora 15. But there is a nice package or software called theme-selector that will help you to modify your default theme on Fedora 15 into something more interactive, more beautiful. TimLau at fedorapeople.com creates some nice theme and packages that is ready to use and works with Gnome 3 on Fedora 15.
This tutorial below will guide you to install Theme Selector for Fedora 15. There are many nice themes you can select and apply to your desktop. See some example in this screenshot below.
yum install http://timlau.fedorapeople.org/files/gnome-shell/extensions/\ gnome-shell-extension-theme-selector-0.9-3.fc15.noarch.rpmThen logout or simply refresh your desktop. Use this combination:
ALT + F2 then type r and enter. You should see Theme shortcut near Applications.