Sherri Betz' videos have been extremely helpful to me regarding how to protect and build my bones. I wish every woman over 60 could know the things she teaches.
I would look at the classes labelled "Osteoporosis safe" (you can search for these using the search icon), and look for slower paced classes. Also review the videos about modifications and contraindications for osteoporosis so that if you watch a beginner class that is not specifically for people with osteoporosis, you can omit those exercises that are counter-productive. Feel free to send more questions about class recommendations to support@pilatesanytime.com and I will try to help.