Instructions
Open the PS3 Theme Builder program on your computer. There are other programs you can use, but none are as user-friendly. If you need to download the application, a simple Google search for the program will help.
Select "New theme" and fill in your name as the author and gaming as the genre.
Obtain a background image for your theme. The dimensions for the image must be 640 x 480. Either download an existing wallpaper or background from a legal source on the Internet, or create one of your own using an artistic program like Photoshop.
Click the "Background, sounds and notifications" tab, then click "Browse" HD or SD background depending on the definition of the television where the image will appear. The finder will pop up, then select the file you copied or created for your background image.
Click over to "Icons, colors and fonts" to further define the appearance of your theme. There are various samples provided. You can build any .png formatted files that are 128 x 128 using Paint or Photoshop to alter the look of your icons or buttons. You can even make them appear only to friends in your network using the options available.
Select "Generate preview" to see what the theme will look like in its complete form. Choose to save it before closing to avoid any errors. Click "Build theme" to finish the process.
Save the file to a thumb drive or external hard drive.
Insert the thumb drive or external hard drive into your PlayStation 3.
Go to theme settings and choose to install your new theme.