As above.
There are some videos on youtube that are very confusing because they explain zeroing a gun with the weapon in a fixed and clamped position, which means you do the opposite to what Piano man has directed by first firing a shot at a paper target and then shifting the reticle onto the point of impact. To do this, the scope has to be aligned absolutely perfectly and the gun kept perfectly still.
With normal 'free hand' zeroing, its best to think of the turrets as controls for the point of impact and using them to 'steer' the pellet onto the mark on the target, the point of aim