First you have to download the save game data from our forums
For this tutorial I will be using the Twisted Metal: Head On save as an example, file names may be different for different games.
1. Open the *.zip file you downloaded. (See Attachmnet #1)
2. Inside the zip folder you will see a folder with a name, usually starting with a "U." (See Attachmnet #2)
2B. Drag that folder to your desktop. (See Attachmnet #3)
3. Now connect your PSP and enable USB Mode then "Click Open folder to view files." (An alternative is to go to My Computer, and open the PSP drive from there.) (See Attachmnet #4)
4. Now you will see 1 or 2 directories (PSP and maybe MP_ROOT). Open the PSP directory. (See Attachmnet #5)
4B. Now you should see three folders (MUSIC, PHOTO, and SAVEDATA). Open the SAVEDATA folder. (See Attachmnet #6)
5. Now you should see some folders with funny names (depending if you have saved any games). It is a good idea to back these files up before continueing. (See Attachmnet #7)
6. It is now time for the final step, and it is a simple drag-and-drop. Drag the folder that you have on your desktop (The one from step 2B) to the SAVEDATA folder (if it asks to overwrite, select YES TO ALL. (Warning, you may overwrite previous save data, please back up these files before overwriting.)
You have sucessfully installed a save file!