I wanna start whit modding but wich programs??? And some good tutorials? Please post it here!
Get pakscape and open up the .pk3 files; poke around and edit the files with notepad, putting them in a directory with the structure that the PK3 files had intact (IE files in weapons/sp folder need to be in a weapons/sp folder). Make your changes and use pakscape to import the directories of the customized files, and name your file zzz-.pk3
Just look around at the files with your notepad, you should be able to figure some stuff out pretty quickly.