I'm reading "The divided Mind" now, but like many reviewers I find it very more difficult, very analytic. I like it a lot, don't get me wrong but it's not the book I would start with.
Which just goes to show how everyone is different,
@Angela8888 ! The only book I read in full by Dr. Sarno was The Divided Mind, and the reason I loved it and still recommend it is:
1. It was Dr. Sarno's last book (and from 2006, there are already aspects of it which are somewhat outdated - but in many ways that's the good news).
2. He goes over his theories very efficiently in the first four chapters. I was already familiar with the power of mind-over-body, so I didn't need to be convinced of that - I DID need to learn about the connection between my symptoms and my
emotions. That blew my mind right open.
3. The remaining six chapters of The Divided Mind are written by 5 other MDs and a therapist, which I found inspiring and exciting - my first hint that there was starting to be a movement towards self-healing in the traditional medical community. The only chapter that I found technically overwhelming was the one on "white coat" hypertension - but I got the gist of it, and it was easy to skim over. And I already knew exactly what that doc was talking about, as I had been practicing relaxation techniques every time I knew I would be getting my BP checked - for years before I knew about Dr. Sarno and TMS.
These two disparate responses to your question about "which book", are your first indication of something which you really need to take to heart:
This work is not linear; There is no one way to do this work; What works for someone else might not speak to you at all.
After you've read Dr. Sarno, my next recommendation is to start doing the Structured Educational Program (SEP). An automatic link should have inserted itself as I typed that

You're in the right place to start finding your own path to recovery - good luck!
~Jan