Instructions
Download save files from any website that specializes in game save files. Sites such as GameFAQs or PSP-saves specialize in files for your console. Download the files to your computer desktop.
Connect the Mini-B end of your Mini-B USB cable adapter to the Mini-B port on the top of your PSP. This cable will come with your PSP console.
Connect the USB end of the Mini-B USB cable to a USB port on your PC.
Turn on your PSP. Select the "Settings" option in the PSP main menu, then select the "USB Settings" option in the settings menu to bring your PSP into USB mode.
Select the "Open Folder to View Files" option on the auto-play menu that appears on your computer. Drag the game save files on your desktop into the window that appears, as this window represents your PSP&'s memory stick.
Disconnect your PSP from the USB cable after you have finished transferring files. The files will now be present on your PSP&'s memory stick. The games you play will automatically recognize the game save files, as long as they are save files for that particular game.