New Super Mario Bros. Tips

Unlock the world 1 cannon!
While in the map go to wi-middle castle. Halfway through that level there is a yellow door with moving blocks inside it, go through a gap in the blocks in the top right corner. When in the room it takes you to get in koopashell and break the blocks to the red pipe, then go through the red pipe and the cannon will shoot you to world 5.
Email me and letme know how it goes :-).