Precision Gun Trackball Wireless How Do I "zero" My Sniper Scope? (air Gun)?

How do I "zero" my sniper scope? (air gun)? - precision gun trackball wireless

Often shot from 40-50 feet, I just want to get it as accurately as possible.
My field is the exact center of the scope 4x32mm Point
The rifle is a ghost (break-barrel), 177 Caliber x1000
Thank you!