The inner blue part is supposed to float inside the lower outer part. That way it is always right at the surface of the water. Set the lower part low enough so that the inner part can float up and down without coming completely out. The hose in the bottom connects to the port that goes into the suction side of the pump. It's usually the lowest port on the pool. The return side, where the water comes back into the pool, should be the higher one. If you have one of the newer pools with 2 suction ports, you may need to plug one of them to get enough water flowing through the skimmer for it to work properly.