I need help to lose stomach fat?

Well, i wouldn't say I'm terribly fat, it's just that I'm not as skinny as I would like to be. I have a big pooch, and I want to know an exericise to lose it. I need an exericse that doesn't include machines. And it needs to be EFFECtIVe!! Please desribe the exericse in great detail. It would help me greatly. Thanks!