The art market is so opaque and illiquid that it barely functions like a market at all. A handful of big names get all the headlines (and most of the dollars). Beneath the surface is a tangled web of dealers, curators, auction houses, speculators — and, of course, artists. In the first episode of a three-part series, we meet the key players and learn how an obscure, long-dead American painter suddenly became a superstar. (Part 1 of “The Hidden Side of the Art Market.”)