Locate the red mark on the gimbal and align it to the unlock icon on the attachment mount. Then screw the gimbal CCW.
Release the gimbal release button when the red mark aligns with the lock icon on the attachment mount. You should also hear a click when the gimbal is securely mounted.
DETACHING THE GIMBAL
Press and hold onto the gimbal release button on the side, then turn the gimbal CW.
Release the gimbal release button when the red mark aligns with unlock icon on the attachment mount. Put the gimbal downward to remove it from the attachment.