Dress like you are going to the gym.  Wear comfortable clothing that you are ready to sweat in.

Try to avoid cotton, as the sweat makes the clothing heavy and will inhibit your movement.  Synthethic materials work well for shorts and T-shirts, as the material helps to wick moisture away from your skin.  REI, an outdoor equipment retailer, is right down the street and has an excellent selection of "moisture wicking" clothing.

During class, no shoes are worn.