The stars are the same of star-superstar level for a player.
If the player u r using is in a spot where he can use some superstar (gold) or star (silver) move, the star appear.
E.g: you should notice a gold star for Tim Duncan when he's in the post on offense, which means that he can make turnaround jumpshot or maybe a spinning hook, depending on the game situation. At the same way, when he's on defese, a gold star means he's a superstar-blocker.
You don't have to do something special to activate those moves as they are automatic.
I hope you understood despite my bad english