One of em is in the Room wih a 1. It`s the Top right door on the bottom floor where you get in. (No not in the moat. =P) There is 2 Peach windows.
Go in the right one. THEN you are at a Slide. Star 1:Slide fast. Star 2:Reach the goal at xx 20 xx. There is a Secret one in the Right door. Go in the right hole. Get ALL 8 Red coins. (Tip:When you are running out of air,Go collect some coins.)