Firmware is indeed key to modding your psp. You can only mod your psp if its at or below 3.03. Basically you'll downgrade from 3.03 (or lower) to 1.50 and then install custom firmware such as 3.40oe-a which will allow you to play homebrew and the newer games. Check your firmware and then start from there. I recommend the Ultimate downgrader sticky as a good starting point. Also, use the search feature on this forum as it will lead you to all kinds of good info.