You want to use the background for all page set up if you want to change the screen on all tabs... Here is a link to the cab, this wall also change your clock to the flip style clock so you need to first install sprint2flip cab.
This thread helps to understand and gives needed files:
http://forum.ppcgeeks.com/showthread...464#post625464
Also there is another way to add the same image to all tabs and not have to change your clock or whatever....
You need this program:
http://forum.xda-developers.com/showthread.php?t=470798 on your PC
Connect your phone to pc via active sync , open cfcguieditor program and go to device/Import from device... this will bring up all your manila files. Put your view type to Manila Name... find file "manila Sprint bg" manila name 4a087e41_manila ... choose your image you want to replace (make it 512x512) use the button, "replace with" and scroll to your new image. This will overwrite the stock background, now click ... To Device (also in bottom right corner) this will set up your phone with the new file.
You're background will be changed on all pages, You can then also select new wallpaper for just the front page via the previously posted methods (gving you custom wallpaper on all tabs with different home page).