Crisscross trailer safety chains in an X pattern when attaching to the truck. With chains crossed, you insure neither side will become too short when making tight turns. Should the trailer come off the ball, the tongue will come down on the chains, allowing you to brake safely without the tongue dragging on the ground. Next, connect the lights, either to a separate pigtail or into the receptacle plug in the vehicle. Have someone stand behind the trailer as you test the brake and turn signal lights. Lock down the catch lever and insert the safety pin. Crank up the jack and wheel or retract it out of the way for transport.