You just log on and register and away you go, you bid for things you want and can advertise any stuff you have that you dont want. Its amazing the things that people buy from there.
Do be cautious when buying nail stuff though it can be overpriced and sometimes its not the real thing.
It's a wicked site .... I have picked up some real good bargains. Always loads of Creative stuff on there... but beware.... they can get to pretty steep prices, and if you aren't careful you can easily overpay!