How To Install Themes On A Jailbroken iPhone or iPod Touch using the summerboard application.
Step 1: Install Summerboard
To do this you will first need a jailbroken iphone or iPod Touch. If you do not have one check out my instructable on how to do so here -->http://www.instructables.com/id/How-to-jailbreak-your-1.1.4-or-lower-iPhone-or-iPo/
First you need to install summerboard, an application that allows you install custom themes for springboard. To get to this go to installer, then to the install tab , then to the system folder to find it.
Step 2: Restart Your iPhone or iPod Touch
You must restart your device to activate summerboard. It will not work unless you do this.
Step 3: Install A Theme
An icon called "SMB Prefs" will now appear, do not use it yet. Next you need to install a theme. To do this, go to the install tab, then to "themes (summerboard)".
Step 4: Change The Theme
Go back to the homescreen and open "SMB Prefs". Next, go to the theme tab and select the theme you want to use.
Step 5: Respring
Go back to the homescreen and wait for your device to respring...
Your new theme is installed with custom backrounds and icons!