How do you unlock all the courses in sonic r

what you do to unlock radiant emerald (last course) is to get all 7 emeralds in the game. Then you unlock radiant emerald and if you come first you unlock super sonic. P.S. if you wanna be sonic go on supersonic or sonic and hold up or down. P.P.S to unlock characters you get all 5 sonic coins on a level and place third or up and you will be racing your opponent.
metal sonic - beach place
toy tails - radical city
dr.eggman (fake one) - ruins place
metal knuckles - reactive factory
super sonic - radiant emerald