Looking for info on my African-American father and his family.

My father was William Martin b abt. 1921 in Jersey City, NJ.
He was married to my mother Kathleen(Francis)Martin in April of 1939.
William died abt. 1955 or 1956
William had sisters:
Minnie Martin
Doris Martin
Wyzetta Martin (not sure is that is the correct spelling)

If anyone can help me out it will be greatly appreciated.