A question about NX

Alrighty, my question is pretty basic however I am still confused by it. How exactly does Free NX offers on MapleStory website WORK? I have tried out some of those surveys and I didn't get anything for doing them. I'd like to figure this out so I can get NX this way rather than spending money I can't on the game (I'd only buy a store permit and pet/pet equips). I checked out basilmarket and there is a guide for doing this, but it didn't help at all. Is anyone here good at getting NX this way? If so, could you give me some pointers so I can stock up on NX , I would greatly appreciate it.