Koopa starts at a place where there are many ? blocks and makes his way through a series of Thwomps that leads him to the door to the next room.
As Koopa jumps across the lava, another Thwomp surprises him, leading to a bridge with Fire Balls. Koopa finally reaches a big red door that will lead him to one of his Goomba friends.
At the beginning, Koopa is surrounded by many ? blocks. Jump to the top of the blocks and quickly jump through the left wall. Koopa will fall onto a platform with a green pipe that'll lead him to a whole different level almost entirely made out of pipes. Make your way through to discover yet another area called "The Power-Up Room", which should help you if you're ever in a jam!
Wario is the boss of this area. To find out how to defeat him, please see this page.