It is simply four lengths of wood, held together by screws, at the measurement determined according to the length and width of your quilt backing.
Remove all the thumb tacks...
Remove the screws and store the wooden rails out of the way.
Then get quilting!
I did get started doing just that and will post again when she's done!
How did you spend your Worldwide Quilting Day? I'd love to see what you're working on!