Help with downgrading

I have a slim psp with a firmware of 3.90. I've been reading up on homebrew, and really want to try it. I also have a GTA/LCS game, but I don't know if it's patched, I know how to find out though. If it is not a patched version, how do I downgrade my psp? And, how do I add CFW to it? Thanks to anyone who can help me.

[brentbizzle]

These are your ONLY 2 options...

With access to a psp running custom firmware: http://www.pspbrew.com/forum/viewtopic.php?t=10137

Without: http://www.pspbrew.com/forum/viewtopic.php?t=11076

Ok, I do not have access to another psp, so I'll be using the pandora battery and magic memory stick. I have to go by these first, but I have already used the total noob program to make a magic memory stick, but when I used it, it just erased everything on it, there was no folders, or nothing. And with the pandora battery, I can't find a good picture of which leg to cut when hardmoding it. Will I be able to choose which CFW is loaded on my psp? Thanks.