To create a sling and swathe, begin with a triangular cloth or bandage draped under one arm and over the opposite shoulder.
Tie the two ends of the cloth behind the neck, as shown at left. Pin the remaining elbow corner up onto the body of the sling. Use another bandage, a belt, or a strap/webbing to secure the arm to the chest, as shown at right.
Procedure, part 1
Procedure, part 2