This is the Kayak Kart. The part with the black foam is obviously the top.
The W500 goes through the square opening and the Top stops just as it gets to the cockpit and is attached there. The wheel part slants forward and stops approx just under the cockpit side of the handles and is secured there.
The W500 is then PULLED to where you want it. If you desire to PUSH the kayak, the top is secured to the handles and the wheels go back towards the cockpit and are secured there. I use bungee cords and small pieces of thin rope to attach.