If the walls in this Great Neck, N.Y., home could talk, they would have legendary stories to tell. The seven-bedroom, six-and-a-half-bathroom home of F. Scott Fitzgerald, where the author first began writing The Great Gatsby, is now available for $3.9 million. Fitzgerald and his wife, Zelda, rented the home from October 1922 until April 1924 during which time Fitzgerald wrote three chapters of his famous novel in a room over the garage. The couple routinely socialized with their wealthy neighbors, many of whom…