How do you get the other part for the carpet on world 1-6?

This is going to be one long answer. First exit the area where the carpet is, but not the fortress completely. Now hit that yellow block and the pathways should switch and you should be able to enter another room on the right. Once you enter the room, well technically outside, two Goombas should have spotted you. Now all you do is avoid the Bombs they're releasing or battle them if you want, but follow the path east. Now you're in another room, hallway thing with the yellow block, whatever you want to call it. Now hit the yellow block and make the floor lead you to the door. Now you should be outside where there is two fans releasing a gust of wind. Just cover those two fans with a Jump, Hammer, whatever sticker you want to choose. Mario should now be able to walk this path easily. Now you're in another, which should be the third, hallway thing with the yellow block. Hit this yellow block until it makes the floor connect with the other floor with the door. Now you are outside again and there are more Bomb-ombs falling from the sky. Use these Bomb-ombs to break the metal fences which should clear the pathway for Mario. Once you walked the pathway you should be in the final room thing with the yellow block. Once you hit this yellow block you notice that the floor isn't moving, it's because you have to paperize! When you paperize you should be able to remove the Yellow Block. Now paperize again and place that yellow block back. Hit the yellow block now and the floor should move. Hit the yellow block until the floor connects with the other floor with the door. Now you are outside, peel the Bowser stick and now you should be on the other side. Good luck you're going to have to face the Megasparkle Goomba after you cross the other side of the carpet.