I want to play some music when you win the game.

Where can I put this subroutine?

According to this thread, if you put it in a subroutine called win_game_jingle, it will execute your own jingle.

Oh, in case you didn't know, the subroutine itself is located in the subroutines{} block. For example:

subroutines {
   win_game_jingle : subroutine {
      // Do your jingle code in here
   }
}