Of all the shades I've had out, there are usually two screws which are imbedded in the shade header. They are usually one to three inches inboard from each end. There is also a catch in the middle which has as tab release. If you can slide the window sideways and pull the screen out, you can stick your head partially out the window to see what's up there. Be sure to "debur " the holes in middle crossbar where the lines pass through. We have been using 96lb Sturgeon fishing leader, same thickness, and doesn't stretch. Usually another set of hands come in handy, cut your new strings at least 6-8inches longer than the original, and check your adjustment bobbin (winder thing) to make sure either one of the two holes isn't broken through.