World 2 consists of desert levels. In these levels, you'll sometimes come across pits of sand. These will slowly suck Mario in, much like water, but can be escaped without too much trouble.
The level starts with a tilting platform to show you how the level's mechanics work. The ? block contains a Fire Flower. Jump over the piranha plants using the platforms and, if possible, destroy them with fireballs. The Red Ring you find will summon red coins from the sky, which can be used to get an extra life. Next, there will be several rotating platforms above a piranha plant. Start by destroying the plant if possible. The ? block to the left contains another fire flower. Then, use the platform to the top right to jump as far up and to the right as possible. There, you'll find the level's first star coin.
After reaching the midpoint flag, you'll notice a yellow pipe. you can either go in there or take the high road. We'll discuss going inside first.
Inside a ? block, you will find a Gold Flower. This power-up turns Mario into Midas, capable of shooting fireballs that turn the enemies and blocks they hit into gold. Blast the enemies and blocks in your way into shiny gold. When you see a ledge in the distance though, STOP! Use the blocks to climb up to the ledge and blast your way to the second star coin. Then you can continue onwards until you reach the pipe back to the surface.
Alternatively, you can take the surface route. This is not recommended however; there are more hazards and fewer coins to collect. That said, the third star coin is on this path, so it is eventually necessary. You will find more rotating platforms over here. The second one contains a fire flower, and the final one has the star coin on top of it. Watch out for the pits below though.
The last part of the level is simple. Simply jump onto the rotating platforms to avoid falling until you reach the flagpole. If you still have the Gold Flower power-up, you'll even get some bonus coins.