You have your opponent in the side mount and they lift their head off the ground.
Come up to your knees and put your head on the ground. Take your right arm round the back of your opponents neck.
Twist onto your right shoulder and step over your opponent with your left foot. Your right hand should be on your stomach.
Grab your right wrist with your left hand making sure you have a tight grip round your opponents neck.
To apply the choke push your stomach forward and pull your shoulders back.