Everyone has to learn somewhere, allalone.

Usually, a master, in the most common sense, does have a mentor that teaches him the way of things, but so do dominants. So do submissives and slaves, for that matter.

Typically, when a person realizes they have dominant or submissives tendencies, they will seek out like-minded individuals to ask questions (Am I normal? and so on). What most people find is a community of people devoted to the safe practice of BDSM or leather or whatever the particular fetish is. Whether that community is online or real life, it doesn't really matter. What's important is that the person with the questons finds a place to have them answered.

Eventually, however, the new, curious person will find someone they seem to gravitate toward because they like that person's style or advice. That's usually when the mentoring begins. This happens more in real life communities than online, however, because the information online is usually readily available by performing a search for it. Which leads to another form of learning alltogether.

It is possible to be self-taught, too. To get your knowledge from articles and books, rather than from another person directly. Many well-known tops, bottoms, dominants, submissives, masters and slaves have written articles, books, and have opened websites for the public's perusal. The only bad thing about being self-taught is that there's no one to answer your questions. If the books, article or website doesn't have an answer to your question, then you might have a heck of a time finding someone that knows that answer.

That's why places like this are so nice to have. It gives people with questions a great place to come to find their answers and gain some extra knowledge.