Swiss chard is primarily grown for its dark green leaves, which can be picked when small and added to salads, or when larger and used similarly to spinach.  The stems can also be chopped and sauteed, adding a celery-like crunch to dishes.  It has a long growing season from spring into late fall and will sometimes overwinter.  
 
Direct sow 1/2" deep in mid-spring and thin to 12" apart when 1-2" tall.  Can also be started inside and transplanted.  Weeding early in the season is important for plant development.