As the others said, you get a 50% share of the wealth made from the models. Might seem unfair at first, but there's been rather intense discussions on the matter and people have concluded that TGC take care of a lot of stuff that is rather expensive otherwise. They use their server space to hold the models, they advertise your model in their application and so on, so in the end it's a pretty fair deal.
It's worth to note that you don't get paid every time a model is sold. Instead, when you reach 1000 bucks sold in total, you get paid by TGC (that means; you get 500 dollars, they get the other half.)
Hope that helps.
