Primary sources give you firsthand evidence on a topic.
Secondary sources, such as books and articles, analyze or interpret a topic.
The library purchases access to many databases containing digitized primary sources. The ones listed here are specifically related to women, but many others could be useful depending on your topic.
For example, Black Thought and Culture has strong coverage of Mary McLeod Bethune, Ida B. Wells, Angela Davis, and many other prominent black women.
There are many collections of primary source material which are available to everyone on the web. Here are a few important ones: