Measure the width of the window and add 8 inches to the total. Purchase curtain rods that will span the width of the window.
Measure 4 inches above and 4 inches away from each upper corner. Alternatively, mark an identical spot at each upper corner of the molding above the window. Hold the mounting brackets up to each mark and mark the screw holes.
Drill pilot holes through each screw hole not backed by a drywall stud or molding. Use a drill bit one size smaller in diameter than the mounting screws. Insert the tip of a drywall anchor into one of the holes and gently pound it into the wall with a hammer. Repeat, filling each hole with an anchor.
Screw the mounting brackets into the molding or drywall anchors. Thread the back rod through the rod pocket of the sheer panels and place the rod in the back bracket. Tighten the tension screws to secure the rod to the brackets. Repeat using the front rod and panels.