Risky P,
The best way to learn is through a good teacher. Usually after 30 sessions you get it...then the concepts are yours for life and you will pay attention and not stiffen and relax. It has helped me alot with stiff shoulders, which would put me on the edge of tears when stressed.
You can read more about it on this good site.
https://www.alexandertechnique.com/there are also several books out there on it. My favorite from the few i know of is:
How to Learn the Alexander Technique: A Manual for Students
by Barbara Conable, William Conable
there are also books on Alexander geared toward musicians, but this book is very good.
You will definitly need a teacher at some point.
Hope you benefit as much as i have !
Good luck and let me know if i can help you more.
S~