to build muscle you need protein. The football coach at my school told it's approximately 1g of protein for every pound you are. So a 175lb guy would take 175g of whey protein.
I *think* that you are supposed to take the whey protein after a workout, but I'm not completely sure. Haven't been taking it for awhile.
As for abs you need to do crunches, eat less and do cardio to burn fat. Atleast thats what I did.
Edit:
http://www.thepumpingstation.com/mus...pplements.html
Theres a site I just googled, it has some explanations of the various types of supplements. Note: they are a store so some of what they say may not be completely true.