Gmat

Hey guys, im thinking of going for a MBA in the near future, i heard that if one has given GMAT and have a good score they are exempted from giving the entrance test? So i just wanted to know what's the procedure for sitting for a gmat exam? how do you pay its fees and from where do you get the material to study for it ?

Usually entrance test is a lot more easier than GMAT/GAT etc, don't know if GMAT is a necessary requirement for MBA these days.