This level is from a top-down perspective and you cannot change the camera angle, plus it is an auto-scroller, so keep up! Snag the Boomerang Flower from the start and defeat the Para-Biddybuds that fly by. Hit the red !-Block with the Boomerang to extend a platform out to the right, so you can get Green Star #1. It is also possible to just grab the star with a boomerang. The blue spots on the ground are ice, so be extremely careful not to slide off the edge, while the reddish orange ones are lava.
In the next area, you must navigate past spiked rollers that rotate around. Make well-timed leaps and stay towards the bottom of the screen, until you reach the ice platforms. Take the pipe for a quick shortcut, then grab the Double Cherry and grab another Boomerang Flower for this next area. The area will be pretty open and a bunch of Para-Biddybuds will be flying around here. You must defeat every enemy in this area, so quickly start chucking those Boomerangs. Once they are all defeated, Green Star #2 appears for you.
It looks like you have reached the end of the stage, but more platforms will slowly move into place. Some Fire Piranha Plants riding blocks will float on by, so either dodge their projectiles or defeat them. When you finally see a bunch of ice and some fire in the middle, shoot a boomerang to collect Green Star #3 that’s over the lava. Eventually, you will start seeing some Stingbies, too, but keep a lookout for the Stamp that’s on the right side; you need a boomerang to collect it. Take the Warp Box at the end, then quickly climb the hexagonal platforms as they appear before the Goal Pole. If you don’t, then you won’t be able to reach the top of the pole unless you have a Cat Suit.