Figure out what type of hypnotist you want, and search for that
"hypnotherapist", "erotic hypnosis", "hypnotic instruction", etc.
If you are looking for just trance training, you can try searching for "hypnotherapist" as well as another category, since many stage hypnotitsts and erotic hypnotitsts also have learned hypnotherapy, and may be willing to train you to trance while knowing that you have recreational motives.