cubic ninja is a game that can be used to exploit, just like zelda oot, web exploit, and mset (original exploit of gateway). these are like acces points (please don't make that joke again). it can start unsigned software (homebrew, or cfw) you'll need to have software to loed what you want to, this can be rxtool, reinand, cakefw, gateway, ninjhax, or any nand/fw (i missed probabl;y a thousand names). each of these tools have pro's and con's. all exploits only work on fw 9.2 or less (realnand) in emunand mode (i don't know the detailes), you can still upgrade to higher fw's. mset only works on old 3ds 4.5 or altered fw n3ds 9.2? so you'll need a lot more to know. ninjhax will allow you to start emulators and homebrew, but no backubs or system cia's? then again you can play most backubs by using sky3ds on any fw (no exploit needed) but most likely you can't use it online.
? marks mean i'm not certain.
did i mis momething?