Washingtonians gather throughout the city Friday to honor the memory of Dr. Martin Luther King on his birthday. A PARADE on Martin Luther King Jr. Avenue in Southeast starts at Good Hope Road, assembling at 8 a.m. (vehicles at 8:30) and starting a three-mile march down King Avenue at 9. That ends with a noontime program of SPOKEN TRIBUTES to King by area children at Covenant Baptist Church, 3845 South Capitol Street (call 724-8062). Sylvan Theater on the Washington Monument Grounds is the starting point for the MARCH sponsored by Stevie Wonder, an effort to make King's birthday a national holiday. The gathering starts at 9 and the march leaves for the Capitol at 10:30 via Constitution. The District's annual MEMORIAL SERVICE is at 10 a.m. with Mayor Barry as the keynote speaker at the Martin Luther King Memorial Library, 901 G Street NW. (An art exhibit showing through January 26 there features calligraphy, drawings and paintings in tribute to King.) Then at noon Mayor Barry asks for two minutes of silence to honor King. Friday evening, a FREE CONCERT at St. Stephen's Church, 16th and Newton NW, starts at 7:30 with jazz, gospel, funk and Andean/South American folk musicians performing. ARLINGTON COUNTY's tribute also begins at 7:30 with a keynote address opening the program of choral music; drawings and writings about King by students will also be displayed at Thomas Jefferson Community Center, 125 South Old Glebe Road. Call 558-2161. And the MONTGOMERY COUNTY's Martin Luther King Jr. Commemorative Committee opens its observance with a showing at 7 of the film "I Have a Dream," preceding the 8 p.m. address by Dr. Thomas Baltimore, Sr., pastor of the People's Community Baptist Church and school mate with Dr. King, which is followed by music and dance. Call 387-4073. Sunday, CORETTA SCOTT KING makes a "Call to Non-Violence" at Washington Cathedral's program to honor her husband that begins at 3:30; Representative Fauntroy speaks as well. At Massachusetts and Wisconsin Avenues NW. Call 537-6200.