African-American genealogy does present special challenges, but they are not insurmountable. Try these sites:
The Freedman’s Bureau Online The Bureau of Refugees, Freedmen, and Abandoned Lands was established in the War Department by an act of March 3, 1865. The Bureau supervised all relief and educational activities relating to refugees and freedmen, including issuing rations, clothing and medicine. The Bureau also assumed custody of confiscated lands or property in the former Confederate States, border states, District of Columbia, and Indian Territory. The bureau records were created or maintained by bureau headquarters, the assistant commissioners and the state superintendents of education and included personnel records and a variety of standard reports concerning bureau programs and conditions in the states.
Ancestry.com Many libraries and local Family History Centers have subscriptions to this collection. The African American collection represents a significant step forward in black family history, dispelling the common misperception that no early black records were kept and that tracking Black family roots is virtually impossible. Representing the 19th and early 20th centuries, the collection has more than 55 million historical documents, including military, census and labor records, as well as a myriad of other black family history records such as photos and narrative accounts from former slaves.
Nantucket Historical Society has these resources: Isabel Kaldenbach’s “inventory of Black Nantucketers,” available at the NHA Research Library, located in the blue file under “Black Nantucket Genealogy,” and now available online. This resource was created by laboriously compiling information from many primary and secondary source materials.
Twenty Families of Color in Massachusetts, 1742-1998, by Franklin A. Dorman.
Frances Karttunen’s article, “The Other Islanders,” available here online.
Afrigeneas provides resources, leadership, promotion and advocacy for the mutual development and use of a system of genealogy for researching African related ancestry. Volunteers on the site post forum messages, transcriptions, articles and more.
AccessGenealogy has a special African-American section.
Those will get you started!