First, remove the old set of grips.
Second, The spring steel piece included with your new Hogue grip needs to be spread apart to snap over the existing locating pin on the bottom the grip frame. It should hang loose from that pin with the screw hole facing away from the grip frame.
3rd, slide your new grip from the bottom of the guns grip frame all the way up to the frame of the gun.
The pin that is in your grip frame of your gun should track along the inside of the Hogue grip.
Once the grip is all the way up on your frame, you should now be able to install the screw from the bottom.
This should snug everything up.
Good luck, Jeff (GUNKWAZY)