Place the rubber hose sections over the seat stay and the chain stay at the point where they meet on the left side of the bicycle. Turn the cam lever out to the end of the bolt. Hold the back plate so that it is vertical like a Y. Slip the back plate between the bike wheel and the stays. The protrusions on the top of the Y should overlap but not necessarily rest on top of the seat stay. The cup shaped protrusion should slip under the chain stay. The casting is resting against the rubber sections. The outside casting is held vertical so that the protrusion on the bottom, opposite the ball, aligns with the cup shaped protrusion on the Y shaped piece and the top fits between the arms of the Y shaped piece.
Turn the cam lever down until it begins to feel snug. When the lever is in the 2:00 o'clock position press the lever down over the cam. The rubber should compress and the hitch feel tight. Give the tongue a shake. If the hitch moves, lift the cam lever and tighten another turn. Reverse the process to remove the hitch from the bicycle. After you learn the process, the trailer can be attached or removed from your bicycle in 10-15 seconds.