You can see it clearly in the last few pictures, you fold out a hook and "hang" it on the screen.

I do exactly the same as Matt: the lamp "sits" on the screen and is leant against the back, so apart from gravity you don't need any aids to attach it.

I have the lamp on a screen. The holder goes a long way down at the back and "leans" against the screen from behind. Really practical and flexible.