Slide the two curtain or valance panels onto the adjustable tension rod just like you would a standard curtain or valance rod.
Hold the adjustable tension rod up on the outside of the top inside edge of the shelving unit on the side that you plan to hang the curtains or valances. Turn the adjustable tension rod so that it will squeeze to fit tightly inside the unit between the sides.
Squeeze the tension rod and insert the ends of the rod between the sides along the top edge of the inside of the shelving unit.
Measure down 1 inch from the inside edge of the top of the shelving unit on each end of the tension rod. Move the ends of the tension rod so that they are on the 1-inch mark for an even installation. Adjust the curtain or valance panels so that they rest evenly across the tension rod.