first open your psp folder then you should see a theme folder drag the theme in to there if not create a new folder in capitals called THEMES in the psp folder.
You make a new you open up the psp (by USB or memory stick) and you go to the folder "PSP" and then make a new folder in there called "THEMES" in caps.
Yes but then how do you change your theme?
How to get themes on the PSP to show up.
You go under settings and you click on theme settings and you choose one. There you can also choose a different color and background.