Shoulder external rotation in side lying with weight

Lie on your good side with a weight in your affected hand.
Keep the upper arm resting on your side and bend the elbow to a right angle.
Keeping the upper arm in contact with the body, rotate your forearm upwards.
Make sure you do not roll back with your body.
Control the movement back to the start position, and repeat.
Ensure your keep your shoulder blades back and down throughout.