I'm guessing this is for NHD, I worked on that too.
One tip is to find a trusty database such as history.com and find articles on the person. These are secondary sources. Another great secondary source is going to your library and getting books on the person.
To find primary sources, look for good pictures of Barbara Kingsolver.
Did she write any speeches or does she have any quotes? These are primary sources.
Hope this helped!