First insert aluminum support rail. Then slide one end of the plastic rail into lower post hole, resting opposite end on the ground. Always work from the empty post. ( The post that has no rails inside.)
Starting away from the pole, slide sheets of plastic through the cut out on top of the rail from one side to the other. Start with the tongue/nub first and cover with trim piece.
Finally, tip the panel forward and slide rail through each sheet and into the entire pole.Then pull back and into opposite pole.
Continue sliding sheets into place until finished. Next, slide rail into pole opposite of trim piece. You can now lock the bottom rail with kippets to prevent movement.