Instructions
Connect a storage media device such as a flash drive or SD card to your computer.
Double-click "Computer" on the desktop. Locate your storage device's icon and double-click it.
Right-click any part of the window, select "New" and then select "Folder" to create a new folder. Name the folder "PS3" (without quotes).
Double-click the "PS3" folder to open it. Create a new folder and name it "THEME."
Double-click the "THEME" folder to open it. Locate your theme on your computer and drag it into this folder. If you're downloading a theme, go to the webpage you want to download the theme from and select the theme you want to download. Follow the guided prompts on the page to download the theme. When you finish, drag the downloaded theme into the "THEME" folder.
Close the folder and eject your storage device.
Connect your storage media device to your PS3 gaming console. Turn on your game and turn on your TV. You should see the XMB menu.
Select "Settings," "Theme Settings," "Theme" and then "Install" to install the theme.