Ok you have to do it this way:
1- You just need to rename the cheat.db to cheat.txt so that you can open it with notepad and write the codes in it.
2- the codes need to be in order first you need to have a file like this (the example is from a FFVII cheat found on this <a href="http://forums.exophase.com/showthread.php?t=3585&page=2">thread</a> you need to put your game info here just use this as a guide)
_S SCUS_94163
_G Final Fantasy VII
_C0 Experience Up
_L 8009BF70 FFFF
so yours should be something like this
_S The game save folder in here, you can see that in cwcheat when you open it while in the game and go to the cheat list.
_G the name of the game goes here.
_C0 Here you put the cheat's name and its C and number 0 not letter O just maaking sure ^^
_L Here goes the code.
3- Now you just need to rename the cheat.txt back to cheat.db and enjoy your cheats ^^
Btw i think the PSX cheats have a different db file something like a popscheat.db or cheatpops.db not sure, (don't have my psp with me to check) hope this helps ^^
