At the base of each leg of the Challenger there are two holes which face each other, one is dimpled , one is not. Place your stake into the hole which is not dimpled , then lever the stake upwards so that it moves down inside the leg tube. Push it down hard to achieve contact with the ground. Do not worry if this slightly distorts the hole in the Challenger leg. It will not affect the structural integrity of the frame. Repeat this process around the rest of the frame and your Challenger will then be secured.