Well, first just mount the metal holders (hook part) onto the panel.
Next, put the panel in place, while holding the clamp part right under where the holder is. You want to mount the clamps slightly below the holders - so that when you close the clamp, it will clamp really tightly.
If you look at the panel clamps, you will see that they use a spring in them. This spring travels about 3 to 4 mm when you have locked it into place... so thats why you want to make sure that the clamps are mounted low enough to make the springs compress a bit.