How do you make a dub?

cause i want to make a sham wow and slap chop dub really bad. for those of you who dont know what a dub is, it is when you take the sound out of whatever you want to dub and add your own sound. if you still dont know what it is then go to youtube and type jabo0odydubs and look at their dubs. i really want to do one but i dont know how to