Unfortunately, you are using an out of date browser which is not fully compatible. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
You might already have an easy way to mark where you put your screw
holes, but I used to have a dickens of a time lining them up. Finally figured
this out, and it helps a lot. I cut an oval mat with an opening 1/8" larger
than the outside size of the frame and a rectangular outside shape. Measure
up the straight sides to get the screw location, then place the mat over
the inverted frame, and it's easy to line everything up for marking.
It really helps. Otherwise, I'd be holding the frame and doing all kinds of
crazy things, trying to figure out when it was exactly straight up, and
whether my marks were level with each other or way off.