The Episcopal Church of the Good Shepherd presents its annual program of readings and music for the season of Advent.   The choir, conducted by Marsha Reilly and assisted by organist Janice Robison and other musicians, will sing music of many styles and many periods.   Following the program there will be a reception and Holiday House with handmade seasonal foods and gifts for sale.   A free will offering will be taken to benefit the June Black Music Fund of the church.