Press "Yes" and wait for the download to finish. This may take several minutes depending on your internet connection.
Select the theme from the board OS7
Press install and wait for the automatic Respring iPhone.
You will, of course, need to have a jailbroken iPhone or iPod touch to install it. Follow our step by step guide posted here to jailbreak your iPhone, iPad or iPod touch with Redsn0w on iOS 4.2.1, or with Limera1n on iOS 4.1, or with PwnageTool on iOS 4.3 if you haven’t already.
Go forth and theme my lovelies! But don’t blame me if the world ends!