How to Find Warp Zones in Mario Brothers

Figure out which Warp Zones are available to you. If you are still in the first two levels (1-1 or 1-2), you can use the 1-2 Warp pipes to get to worlds 2, 3, and 4. If you are already past World 1-2, then you can only use the warp pipes in world 4-2. If you are past World 4-2, it's too late to use any warp zones.

Jump up the elevators in world 1-2. Just towards the end of the level, there will be a series of steel platforms going down, then a piece of land with bricks over it, and then some steel platforms going up. Jump from the down elevators onto the bricks, then forward onto the up elevators, and then take a running jump from the top of the up elevators forward onto the ceiling.

Continue running forward until you see three pipes below you. Fall into the hole on the screen to access the pipes, stand on top of the one numbered with the world you want, and press down. Note that the pipe to World 4 is the fastest way to the next Warp Zone.

Run past the first set of Question Mark blocks in world 4-2. Just after you jump past the elevator, you will see a few bricks in the air. Jump up under the leftmost brick, and you will hit an invisible block.

Jump up onto the formerly invisible block you just revealed, and break the two bricks that are in your way just above you.

Return to the ground and jump up just to the left of the first blocks to reveal another invisible block.

Stand on top of that block and jump up to hit a block that will produce a vine. Climb the vine, follow the path, and you'll be at the Warp Zones to worlds 6, 7, and 8.