Obviously you could just book yourself into one of the seminars that are offered on this site dedicated to them:
https://www.bengstonworkshops.com/
However, if that is inconvenient, you like to have the material anyway or love to learn at your own pace you can get it from Amazon and Soundstrue.com.
I got mine from Soundstrue.com in 2010 and I think it is still unchanged. I would guess 95% of it is still current although Bill mentioned a few additional discoveries he made over the decades in some of the YT videos that in some cases lead to minor adaptions in how the process is applied. But none of this is critical, if you learn strictly "by the book" no harm done. The rest are just add-ons so to speak.
https://www.soundstrue.com/products/hands-on-healing
If you happen to be in India you can get the audible version for a little over 8 bucks here:
https://www.amazon.in/Hands-Healing-Training-Course-Energy/dp/B079K4GV64/
