You need to finish at least -1 on each course in the game using your created golfer (fantasy and PGA pros don't count).
There are 16 courses, of which several are unlocked as you play through the Tiger Challenge. It is easier to play a PGA Tour Season on easy or balanced difficulty settings, with one round per tournament. The PGA Season hits all 16 courses at least once, with four repeats that you can skip if you like. On the lower difficulty settings, you should be able to beat par without much effort.