A primary source is a first-hand account of an event (diary), the actual item, document, or work (United States Constitution).
Primary sources can include
Interviews, diaries, letters, journals, speeches, autobiographies, and witness statements
Articles containing original research, data, or findings never before shared
Original hand-written manuscripts
Government documents and public records
Art, photographs, films, maps, fiction, and music
Newspaper and magazine clippings
Artifacts, buildings, furniture, and clothing
A secondary source is something written about the event or work (a critical essay discussing the imagery found in the short story, A Rose for Emily), a biography about a Thomas Jefferson.