Put the plates down on the bottom of the bare tank. Connect the plates together. Put the riser tubes on. Put the gravel on top. Install the air stones in the bottom of the riser tubes and feed the airline tubing through the elbows at the top of the riser tube. Hook the other end of the airline to the air pump. Put the pump higher than the tank.
Fill with water. Turn pump on. The rising bubbles brings water up the riser tubes, in turn, drawing water down through the gravel. The gravel acts as the filter. Good bacteria will live on the gravel that will break down the fish waste. Don't ever scrub or bleach your gravel, just siphon it clean every now and then.
That should get you going. Need anything more specific, just let us know!

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