My first experience modding my Mac was simple and fun, but that's because I have a Mac genius husband to guide me along. If you are interested in personalizing your login screen, here is how it is done...

First open Terminal and type this:

sudo defaults write /Library/Preferences/com.apple.loginwindow DesktopPicture "/Library/Desktop Pictures/Nature/Clown Fish.jpg"

Then hit enter. Terminal will then prompt you for your password. Type it, hit enter, and then restart the computer. That's it!

Of course you can select a picture of your choosing. Just type in the location and name of the picture you want instead of the one in this example.  Josh tells me that you can use any picture in the "/Library/Desktop Pictures/" folder, or if you want, you can put a picture of your own in a public area of your hard drive such as "/Users/Shared/". This trick works with Tiger, Leopard, and Snow Leopard.

Have fun modding your login screen!


Before: Aqua Blue desktop picture behind the login window


After: Custom desktop picture behind the login window