Read this entire document.

If you don't understand, then you're hooped.

http://doc.kodewerx.net/index.html

 

lern binaty lol tat's basicly wut tey r. also i hax so i know tese tinghs



How to hack a code (simplified).

Get an emulator, because you're not going to have the hardware needed for code hacking on hardware.
Look for the "search for cheats" button. If there isn't one, something that hooks the process might work, although it will get messy later on when you have to convert it to an actual code.
Locate the address you want to edit by elimination whilst playing the game.
Change the value in memory
Done.