Beat world seven.
beat level 7a
Beat world 2
if you mean ds,beat world 2's boss as super mini mario.
go to the 5th world and beat the boss as mini Mario
beat the last level in world three
beat the boss with mega mushroom
Beat 7-4
Beat Bowser simple :)
You need to beat level 2 and 5 as a mini mario to get to them worlds
dance
After you beat a boss you can save. Or if you have already beat a world you can go back to that world and save anytime