See those two little screws near the top??? Take out the filler screws and that's where you screw in the peep sight.
I'm gonna put my FlameSuit on - - Just in case

IF you're going to put a peep site on it you need to do one of 3 things:
1. Have the correct screwdriver!
2. If you don't have the correct screwdriver buy one!
c. If 1 or 2 don't work for you - Take the gun to a gunsmith to have the screws removed.
3. Treat them like they've been glued in when you remove them!
I don't mean to be insulting, but I've seen some fine firearms hurt because of something as simple as a slipped screwdriver sometime along the way. Totally unnecessary......