Answer:
In 1957, tennis player Althea Gibson won the women's championship at Wimbledon. Later that year, she became the 1st African-American woman to win the US Open.
Explanation:
Any requirement of spell check includes the checking and correction of the spellings of the words and the correct usage of the capital letters where needed. This also includes the correct usage of the punctuation signs according to the sentence.
The given sentence needs some changes in its use of the capital letters for those proper nouns such as "Althea Gibson/ Wimbledon/ African-American/ US Open".
Thus, the correct and final sentence is-
"In 1957, tennis player Althea Gibson won the women's championship at Wimbledon. Later that year, she became the 1st African-American woman to win the US Open. "