AFTERNOON AT THE OPERA: Beverly Sills: The All-American Diva. Brooklyn-born and American-trained, Beverly Sills became an operatic and media superstar as much for her vibrant personality as for her expressive and beautiful voice. She blazed her own trail to stardom, and only ventured to Europe and the Metropolitan Opera after achieving enormous success as a singer. Upon her retirement in 1980, she channeled her energy to become one of the premier arts managers of her generation, as general manager of New York City Opera, chairman of Lincoln Center for the Performing Arts, and Chairman of the Metropolitan Opera. She became the best fundraiser the arts had ever seen, and also devoted herself to charities such as the March of Dimes. Presenter Marc Courtade is the business manager for Tilles Center for the Performing Arts at Long Island University, and producer and artistic director of Performance Plus!, a pre-performance lecture series. He is a frequent lecturer for the Hutton House Lectures, specializing in musicals and opera courses, and adjunct professor in the arts management curriculum. An avid performer, Marc has appeared in numerous productions throughout Long Island. 3 p.m.