Instructions
Choose a photo or image that you would like to use on your Sony PSP.
Resize the photo to a 480 x 272 pixel image using your computer's standard paint program. Use the edit function, and enter the image size manually.
Save the new photo to your computer's hard drive.
Transfer the image to your PSP. This can be done from a Windows computer or a Macintosh computer using the step-by-step instructions in the PSP manual on transferring photos to and from your Sony PSP. In most cases, you will use the data transfer cable that came with your PSP to connect through the USB port on your computer to transfer the images over. This will save the image onto your PSP.
Load up the image browser on your PSP by selecting the "Photo" image on the main menu, and select the source in which you saved the background image that you want to use, whether it be your system storage or a memory stick. Select the "X" button to zoom into the photo and display it on your PSP screen.
Press the "Triangle" button on your PSP to bring up the menu, and scroll to "Set as Wallpaper."
Press the "X" button to choose the wallpaper. You will be presented with a warning screen stating that you will lose the current wallpaper image. Press the "X" button to proceed.