This stage is Switch Scramble Circus (1-5). This complete walkthrough will provide you with a 100% video playthrough and a screenshot of where you can find all the green stars. We will also note a secret Fire Flower.
Game Play Walkthrough Video
Green Star 1
The first star is located on top of the question mark box. Use wall jump or cat climb to get to the top and claim your first green star.
Green Star 2
Make sure you collect the secret fire flower when it comes up. With the flower flower, you can destroy the secret room when you hit the question mark box. The second Green Star is located at the upper left of the room.
Green Star 3
You won’t miss the last star. It’s located at the center of the room near the end of the stage. Simply be careful of the wizard’s fireball while getting it.
At the end of the stage, trigger all of the blue floor tiles to lower the platform. You will then be able to grab the stamp.
Other Notable Secrets
By collecting all 8 red coins after you trigger the red ring, you will obtain the Fire Flower.