Instructions
In the first room, try to make your way to the top-right corner. Don't enter the door that is instantly visible. Instead, walk through the wall on the right and enter the newly revealed secret door.
Climb up the ropes, collecting coins and avoiding ghosts in the process. At the top of the room is your door. It may not be a secret, but is the right step to continue the level.
Reach the horizontal rope at the top of the room and climb on it. Reach its far-right end and wait for the floating platform to come below you. If your timing is right, Mario will fall onto it. You should be able to see a narrow fixed platform on the left. Jump onto it and a new secret door will be revealed.
Watch out for ghosts as you begin to fall on top of a descending platform. Be aware that the falling speed does not remain the same and that you will find yourself traveling down at immense speed. When you have reached the bottom level, enter the visible door.
Make sure you avoid the ghost before reaching the flag and you will have successfully passed the level.