Wing chun footwork/practicing the forms?

I've done research into wing chun and has taken a few cles and got books and do other martial arts, but i was wondering, how does wing chun footworking work? Also, how do you properly practice siu nim tau, chum kiu, and biu tze? I've heard you have to like set up triangles in your stance (the common wing chun stance) where precisely are these (and how u use it also for a thrusting punch)? And one last question, how do you achieve internal power from practicing siu nim tau? Sorry if i seem like a noob, but i've just been wondering about these for quite some time now.