1. This is a job for two people. Unpack the light frame. Form it into a "C" shape and suspend it over the top of the uprights. You can form it with the knobs on the inside or the outside. Make sure the knobs are backed out far enough to allow it to slip over the top. Slide it into desired position.
2. Use the knobs to tighten it down. It does not have to be super tight.
3. Now drop two sheet metal screws with washers into the holes in the top of the long bar.
4. Turn the light facing down, and locate two nylon fasteners.
5. Position the light under the bar with the two screws positioned to go into the nylon fasteners. Insert the screws and tighten them until the light is secure against the bottom of the light frame bracket hinges.