Position the curtain rod and curtains over the doors. The curtains should just meet the floor and the rod should be evenly centered over the glass door. The rod should be a few inches above the window and header. Use the pencil to mark where the holes on the bracket are as well as where the edges of each bracket are. Use the level to make sure the rod is even.
Drill a hole in each pencil-marked bracket hole. Use a drill bit that is slightly narrower than the anchors. Start with the holes for the center bracket, then drill the holes for the brackets on each side.
Push the anchors into each hole. Use the hammer if needed to knock them in until the opening of the anchor is flush with the wall.
Set the brackets against the wall again, aligning the holes on the brackets with the holes in the anchors.
Put the screwdriver bit on the drill and drill the screws into the holes. The screws will hold the bracket in place and will cause the anchors to split apart behind the drywall, creating a secure mount.
Attach the curtain rod to the brackets to hang up the curtain.