First off position the ring where the screw hole will be at the bottom. Then you'll notice one of the clips has a "rectangular" tab sticking up on it. This one goes at the top and the "tab" will fit down in a slot at the top of the headlight bucket. One is long as you can see in the pic below. The other two go on the side.... If your using the new repop spring clips they sure don't work as good as originals!!
Not sure about the screw. Got to your hardware store and buy you a #6,#8 sheet metal screw about 3/4" long and pick the right one. They're only about 6 or 8 cent a piece.
EDIT: here is picture of the retaining clips
http://i140.photobucket.com/albums/r19/LutherParris/52Panel/img009.jpg
