How old is she? Did you get a corner litter box or a small cat box? How big is the cage, how many floors? I would suggest getting a couple small cat boxes if the cage is a couple floors. Note where she goes to the bathroom at and place the litter box there. Have a couple outside the cage too for when she's out playing. Most ferrets prefer to have their whole body in the box when they go to the bathroom, that's why corner boxes don't go over well.

As for the nipping, what do you mean by that? Does she just walk up to you and bite? Or bite when you're playing? Or startle and bite? If it's walking up and nipping, scruff her, drag her about 2 feet and let her go, then ignore her. If she's biting when playing, that's normal. She may though, bite harder then you'd prefer, that's because a ferrets skin is thicker then ours so they don't realize they're hurting us. Just scruff her and say no if she bites too hard. Scruffing is pretty much the answer for everything!!