Suggest 'LIght on Yoga' by Iyengar, a $50 yoga mat, mute button on all devices, one hour per day 3X per week for one month at home. But don't think 'only back' but strong legs, abdomen, thoracic spine, etc.
This route takes more personal effort rather than relying of paid help but such dedication will strengthen your mind/body and such responsibility can last a lifetime.
Or of course, you can also get started with a yoga teacher. Nothing wrong with that and if possible, find an Iyengar teacher.