As with most projects, the crucial question with hanging wallpaper is where to start. King's Smartn' Up wallpaper stores have had to answer enough questions from people trying to hang wallpaper themselves that they started giving free classes on the subject. Conducted in the two stores, several times a month, the classes begin about 7 p.m., with how to measure and prepare a wall for papering. They go on to actually paper a wall, and finish a couple of hours later after answering questions, which, manager Herbert Schwartz has found, "are pretty much the same from class to class." Generally, people are concerned about how to handle corners and match up designs. So far, no question has stumped Schwartz, but he promises to look up the answer and send it along if that ever happens. For people who are still squeamish by the end of the class, Schwartz gives them some paper and paste and shows them to the practice corner so that by the time they leave, they know that they really can do it themselves.

Wallpaper classes. King's Smartn' Up, 2808 Graham Rd., Falls Church (560-4700); and 6228 N. Kings Highway, Alexandria (765-0800). Evenings, 7 to 9 p.m. Free. Call to reserve space.