Lock both hands around the band (or handgrip) and pull arms diagonally across your body. Twist your torso while keeping your abs contracted, back straight and arms fixed in a slightly bent position.
Tips:
Center your body weight over your feet and your head over your shoulders.
Rotate shoulders and hips together as a unit with abs.
Variations:
Raise or lower A.P. height:
A low A.P. height will require you to pull the band across your body at an upward angle. Pull at a downward angle when using a high A.P.
Pull band horizontally across body when using a chest-level A.P.