Add the first and last pickets (far left and far right) only use one screw in the center of attachment points. Now you should be able to adjust your rails. Obviously you need to measure and be sure that your rails are parallel and straight. Now start filling in the middle one side to another- I went right to left. You should stagger the screws in a "v" pattern to increase rigidity (check out photo) As you add pickets you should notice the door becoming more rigid. By the last picket the door should be straight and not droopy. When I was done it worked great, except when it swung out the door would touch the ground and I noticed the right post was bending from the weight of the door extending outward. Thats when I added the top "stabilizer" bar (second photo), this is esstential to the design. Mine is screwed into the top of the right and left posts and then butts up to my house. I need to add an angle bracket to anchor it to my house to keep the posts from swaying outward when the door opens, although that doesn't seem to interfere with the doors function