This last pic is great. The the white airline on the left is your air control line. This configures the amount or air that mixes in the chamber creating bubbles the tube on the right is for the overflow cup. That needs to be out of the water or you are essentially putting everything you just skimmed out right back in the tank. The numbered dial is he water level indicator. It will adjust how high the water is inside he skimmer chamber. They will work best if you have an ATO to keep the water level constant, otherwise you will be adjusting that to keep it the right height.
Fish are people too!!!