Contact community colleges in your area that offer continuing or adult education programs. Many of these programs offer specialty massage classes.
Ask if there are any continuing education credits offered for taking the course. This is important to track, especially if you are a registered massage therapist and want these credits to count toward your requirements.
Contact the American Massage Therapy Association for upcoming classes on Thai massage. This information is also available on their website.
Contact a school specializing in Thai massage. Schools such as the Thai Institute of Healing Arts and Soma Veda Integrated Traditional Therapies are based in the U.S.
Consider studying Thai yoga and massage in Thailand. Study tours are hosted by the International Thai Therapists Association.