Enable codes?

[ChaosVexus]

How do you exactly find them out to make them work on the games they are for?
I kinda need help for finding them for: Pokemon white & black 2, rings of fate FFCC, FFCC EOT, Pokemon explorers of the skyFF4, Kirby super star ultra. I am not sure how to get these enable codes first time using a ds,dsi,dsi XL, & 3ds gamegenie mostly used the AR but eventually these things break & can't find anymore in my town so idk how to locate such codes help?