sorry in advance
if it starts, its good.. if not well its either bad, key is not on, battery is dead, in gear and you dont have the clutch pulled.
ok now on a serious note, best thing i could recommend would be to pick up a good service manual (clymer, or the factory service manual).. i know on a buddies 125 the starter didnt work and he just had to open it up and clean all the dried mud out of it lol