Quackwatch is an excellent resource for learning about chirporactors! And a bunch of other types of treatments as well. The articles there will help you find a good chiorpractor and also help you sniff out quacks everywhere. IMO.
In the US, a chiropractor graduates from a school of Chiropractic “Medicine”, where they learn about subluxations and spine alignment, and, even today, things like “life force”. Good chiropractors will open up private practice and offer treatment for back pain, and other muscular-skeletal kind of issues. A chiropractor who talks about life force and helping your sinuses is a full-fledged quacker. My primary care physician for almost 10 years was an osteopath. She has a Doctor of Osteopathy degree from a College of Osteopathic Medicine. I could tell no difference in the treatments I received there from other MDs I have been to. Except, maybe, she was better than most. The other major difference between MDs and osteopaths is that osteopaths also study chiropractic treatments, although my doctor never once offered to treat my asthma or allergies with spinal manipulation.