what do i do after Breezesong/star becomes leader of FireClan?
After Breezesong becomes leader of FireClan, if you agree to meet up at the border every night, you can learn more about FireClan and eventually be allowed to go over into their territory (and adopt kits if you want to if you're mates with her). If you don't agree to meet up at the border every night, then you leave FireClan alone for the rest of the game. There is really nothing else significant after that point besides some optional quests, but the game doesn't have an actual ending at this point, except for dying or quitting the game.