Learn from the stars: At the Kathleen Ewing Gallery, silk-screen artist Lou Stovall will discuss and demonstrate "Techniques of Silkscreen Printmaking" beginning Thursday, July 18. There is a $40 fee. For more information call 328-0955 . . . Guatemalan Roberto Cabrera's arte correo (postal art) resounds with the controversial political dialogue that continues in his native region. At Fondo del Sol gallery through July 17 (483-2777) . . .

In from the West Coast, "California Black Printmakers" highlights the work of Margo Humphrey, John Riddle Jr. and other prominent California gallery exhibitors. At the Howard University Gallery of Art, College of Fine Arts (2455 Sixth St. NW; 636-7070), through July 31 . . . Eight talented recipients of Kennedy Center Summer Fellowships for Teachers of the Arts will give a free multimedia performance in the Kennedy Center Theater Lab, July 16 at 8 p.m. (872-0466) . . .

In celebration of the National Endowment for the Arts' 20th anniversary, President Reagan has designated Sept. 23-29 as National Arts Week . . . A pleasant surprise greets museum goers at the Arlington Arts Center (3550 Wilson Blvd.; 524-1494), where "Recent American Works on Paper," curated by the Corcoran's Ned Rifkin, runs through July 27. The Smithsonian Institution Traveling Exhibition Service plans to circulate the show nationally for two years after it leaves Arlington.