The metal piece at the top of the door just slips over the top of the door on the inside. It also needs a belt weatherstrip to seal against the window glass. From there, you need to attach the panel board to the metal piece and trim it to fit the door. You can attach the belt weatherstrip with staples, stainless steel or aluminum pop rivets, or very small flathead screws.
Your car is an easy one to get OEM door panels for. Are you looking to make the door panels custom, or do you want stock door panels?
No one lives forever, the trick is creating something that will.