In dungeon levels like world 1-2, there will be a warp zone. I will tell you how to go to this so called warp zone by explaining it in world 1-2. So anyway, at the almost end of the level at the part with the platforms, jump up to the ceiling at the end and keep running. It will say 'WELCOME TO WARP ZONE!'. you can pick which world you would like to go in.