Click 4 board corners in order: top-left, top-right, bottom-right, bottom-left.
After calibration, the preview shows an 8 × 8 grid.
In Finger Touch mode: finger down = grab, finger up = drop.
In Pinch mode: use Cal Pinch Open and Cal Pinch Closed, then Save Pinch Cal.
Reverse Palm / Back helps if one hand is read backwards by the camera.