Make sure all parts are included. You should have:
An optics mount
Make sure the pistol is unloaded and safe.
Install your optic onto the mount using the 6-32 screws that came with your optic. Inspect the bottom of the mount to make sure the screws don’t protrude below the bottom of the mount as shown (Docter pattern mount shown):
Install the optics mount onto the pistol, using the original screws.
Perform a function check and make sure the pistol is safe to fire.