Face your partner.
Reach out and place your hand on the inside of your partner's opposite forearm. Your partner will do the same to you. You won't actually grip each other's elbow, but you will firmly hold each other's forearm just beyond your elbows. While your grip should be firm, do not squeeze.
Turn in a clockwise direction if you are holding right forearms with your partner. Turn in a counter-clockwise direction if you are holding left forearms with your partner. You both will be moving around the other person, with your grip remaining in the center of the turn.