The intake should be a "U" like shape. One end of the "U" will be smaller than the other. On this end, attach the small pipes and strainer. On the other end, it should be wide and have a spot for the impeller to attach to. The impeller will have a rubber stopper on each end of a metal rod with a silver magnet and a piece of blue plastic with arms sticking out in the middle. On the fat end of the "U", stick the rubber stopper with the blue plastic with arms up into a small hole in the center. Stick the end with the impeller assembly into the hole located in the well on the right side of the filter. Fill the wells up with water and plug it in. You will need to buy filter cartridges for it, and the size you need should be listed somewhere on the filter. Stick the cartridge in the slots on the left side of the filter. You should also have a piece of foam in a plastic frame. Stick this in front of the cartridge with the side that has all the squares facing the cartridge. Hope this helps.
They do work decently, but IMO they aren't the best. Might want to switch to an Aquaclear filter or something else.