Can someone teach me how to play Doom on my PSP?

I am extremely new to this whole PSP/Emulator thing, I just got my PSP a few days ago. I was doing some research and I came across this site. I originally had v2.00, then I downgraded back to 1.52. Is there somewhere that has a step-by-step guide to being able to play Doom, and if possible, other ROMs on my PSP? That would be VERY much appreciated.

u need 1.5

RE-Upgrade to 2.00 then downgrade to 1.50, Then we'll talk.

Ill try again, I have a feeling that because i had the Madden UMD in it when i downgraded from 2.00 and it automatically upgraded to 1.52. But I will try again.