Tomorrow marks the beginning of Kwanzaa, a seven-day celebration progressively becoming a tradition in the lives of many black people in this area and across the nation. Initiated in 1966 by black nationalist Maulana Ron Karenga, Kwanzaa -- which in Swahili means "first fruits" -- gives blacks a way to honor their African heritage during the Christmas season.

Patterned after African harvest festivals, each day of Kwanzaa is devoted to one of seven principles, called the Nguzo Saba. Each principle underscores a tenet regarded as essential for a community's social, political, economic and spiritual advancement as well as for the well-being of individual families and races.

The principles are: Umoja (unity), Kujichagulia (self-determination), Ujima (collective work and responsibility), Nia (purpose), Ujamaa (cooperative economics), Kuumba (creativity) and Imani (faith).

Similar to celebrations in other cultures, Kwanzaa uses tangible symbols to express intangible ideals. The symbols of Kwanzaa are: the mkeka , a straw mat which represents the foundation of the African family; the kinara -- a candle holder for seven candles -- representing the African ancestors who are said to be the fathers of mankind; mshumaa , seven candles, representing the seven principles. Mhundi , ears of corn, represents each member of the family. Mazao -- crops -- represents the fruit of labor, while-zawadi -- handmade gifts -- represent the rewards of achievement.

Children, who are given a special role in Kwanzaa, are encouraged to make house decorations using the Kwanzaa colors of red, black and green. Each day of Kwanzaa, families and friends gather to light the candle for the day and those for the previous days, starting with Umoja . Out of the Kikombe -- unity cup -- juice or wine is poured on the ground in honor of the ancestors. Following the libation, the cup is passed to each person, who then drinks and exclaims, "Harambee!" translating into "Let's pull together." Then, the particpants discuss the principle of the day. On the last day of the celebration a karamu -- neighborhood feast -- is held.

Several thousand Maryland and District residents are expected to participate in private and public Kwanzaa celebrations this year. For those who have questions about Kwanzaa, employes at the Museum of African Art will teach families how to organize a celebration properly.

The following are free, public celebrations:

The Temple of the Black Messiah will celebrate Kwanzaa at Ujamaa Shule school, 8th and Q streets NW. The events begin at 6:30 p.m. every day except Thursday, Jan. 1, 1981, when there will be a High Celebration at 8 p.m.

The Museum of African Art will sponsor Kwanzaa afternoon observances and evening performances by African folk singers, dancers and drummers. Events will be held either at the museum, 316 A St. NE, or the Baird Auditorium, Museum of Natural History at 10th Street and Constitution Avenue NW. For more information, call 287-3490.

Other Kwanzaa events will be held at various locations by a coalition of several businesses, private schools and organizations:

Friday, Dec. 26: Umoja day will be celebrated at Watoto Shule at 8 p.m. at the Watoto Shule school, 770 Park Rd. NW.

Saturday, Dec. 27: Also at Watoto Shule, a "Children's Party," will be held between 3-6 p.m., followed by a Kujichagulia day celebration at 8 p.m.

Sunday, Dec. 28: Ujima day will be celebrated at the Calvary Methodist Church, 15th Street and Columbia Road NW at 8 p.m.