First question... what do I need to edit my pokemon? I already have the pokesav for heartgold and the original game.
There's a basics guide on projectpokemon, the same place you got pokesav. Once you get the basics down, we can talk about more advanced stuff.
You need a way of getting the save file off of your cart. That can be done through a slot-2 flash cart or a gameshark or something.