Never mind. I used the eye-hook method instead.
For those who want to know.
1. Get two eye-hooks form lowes/home depot (about 3" long)
2. Screw them into the two studs at each end where your screen goes. (make sure the appropriate height)
3. After you assemble the frame (and before the screen material), rest the bottom of top aluminum tube on to eye-hooks
4. Adjust horizontally and mark the eye-hook holes on the bottom of aluminum frame.
5. Drill the through hole at the markings.
6. Inseer a bolt of about 1.5" and fix it with a nut into the drilled hole (Top of the bolt is on the top and the bottom portion hanging out (and tightened with the nut).
7. Insert the hanging part of the bold into the eyehooks when you are ready.