[header] How to install vertical blinds [title] Screw holes into the valance. [step] The valance is l-shaped so the top surface can be mounted inside the upper frame and the front of the valance will hide the headrail. [substeps] Place the valance on a flat surface with the front of the valance in an upright position. 
Measure 3 inches (7.6 cm) from each end and position each bracket so the top edge is against the upright valance. Use a pencil to mark the 2 screw holes in each bracket.