Do a search. There is a lot of information on here about supplements in the supplement forum. Most common right now is hydroxycut and animal cuts though, I believe.
You need protein, protein and protein first and foremost for any muscle gains. Yes, you can make gains without supplements, but they will be VERY slow in coming if at all. Most people cannot gnaw their way through enough protein to meet needs for muscle gains. A good meal replacement is also a must for losing fat. As mentioned Hydroxycuts or one of the "fat burners" may be used, but realize one thing. They are best utilized at the beginning of a training session to help boost your metabolism. They will do nothing taken and not changing your diet. This is a rare occruance at best. Proper nutrition and exercise with the weights and some cardio thrown in are your best bet. Muscle mass is the best fat burner there is! The more muscle mass you have, the more fat you burn even at rest than the average "Joe".