Ok the very first thing you'll have to do is download the cwcheat package and the latest DB (database)
Links are below...
After that on the psp go to SETTINGS>SYSTEM SETTINGS>SYSTEM INFORMATION and you'll see your firmware version ending with letters, WRITE THIS DOWN ON PAPER: YOU'LL NEED IT LATER!
Now plug in your psp through a usb cable or a card reader for memory stick.
Go to the root of the memory stick, there should be a folder named "SEPLUGINS". If not then make a new folder named 'SEPLUGINS'.