Basically pnach files are lists with RAW cheats formatted in specific way, if you want to use existing cheats or convert ones you created yourself, you don't really have to learn much if anything.
Just grab PCSX2CE and Omniconvert
, then use the latter to convert codes to raw(if they aren't already) and add formatting either manually(yeah you could create pnach file in notepad or any other simple txt editor) or with linked program(it has it's own step by instructions there as well). In the end you just put pnach file in cheats folder and activate cheats in pcsx2 then refresh the gui by any way you want(moving a slider in the log works;p, you could also use F1/F3 to save and load, or even restart the emulation), that's all.
If you can't find some cheats couse they don't exist yet, don't work in your game version or simply you have no idea how to use google(
) you can always check this overgrown cheat thread
which we use to share our codes and help each other with cheating related stuff, it also contain some links to more info, just note that some of that info is outdated, from my personal experience it was actually more confusing than simply looking at some examples, but that will differ for everyone I guess.
Just remember that if you request some cheats always post the exact code of your game(those codes start from SLUS, SLES, SLPS and similar) or at least tell which region/release do you have couse different ones need different codes and if you want a ready to download pnach file also your game CRC number as the filename of pnach file must have it. Both of those can be found in pcsx2 log after running the game.
Also that thread index wasn't updated from a very long time, when searching for cheats/pnach files you can use google to search through it easily by copying in google:
site:http://forums.pcsx2.net/Thread-Post-your-PCSX2-cheats-patches-here "game title"
Good luck and don't think too highly about pnach files;p, it seriously is NOT as complicated as it seems at first and pretty much everyone can learn how to use them.