Yoga students are men and women, young and old, with a variety of body shapes and degrees of flexibility. Most postures can be done at any level of difficulty. Yoga emphasizes the experience of moving through the postures with mindful attention to detail, and staying focused in body, mind, and breath. In yoga, there is no competition and no need for self-judgment. Loose, comfortable clothes are best.
Some people wear tights and t-shirts, some wear shorts or sweat pants, and others prefer leotards.
Wear whatever works for you. This is your time, so enjoy it. T'ai Chi classes and special classes in body movement.