Summarize this article:

Place your right hand on your partner's upper back, just below their shoulder blade. Then, keep your right arm under their left arm, and hold your partner's left hand in your right hand. In dance, there's typically one partner who sets the pace, called the leader. In traditional male-female pairs, the male is usually the lead, but that doesn't always have to be the case! If your partner is the one who's leading, place your right hand on your partner's shoulder and rest your left arm on their right arm. Clasp your partner's right hand with your left, bend your elbow slightly, and hold your hands up at about chest height. No matter which position you're dancing in, try to avoid having a stiff posture while you're swing dancing. Walking in place while facing your partner is a simple way to dance East Coast Swing. You can also walk together from side to side, or forward and backwards. Make sure that your partner steps at the same time using the opposite feet as you do. For example, if you take a step with your right foot, then they should take a step with their left foot, and vice versa. This is called a rock-step. While facing your partner, take a step back and put all of your weight on that back foot. Your partner should also step back and rock back as you do, but using the opposite foot. For example, if you step back with your left foot, then your partner should step back with their right foot.

Summary:
Place one hand on your partner's back if you're leading. Hold your partner's shoulder and opposite hand if you're following. Take 2 slow steps in place while mirroring your partner. Step back and shift your weight to your back foot, then step forward again.