Reference materials like encyclopedias, a good biography found in our catalog and so can really help here.
Then start your search. Think of things like articles from magazines or newspapers during the time the person lived, or the event happened, books they wrote about their experiences, that sort of thing. There often is more of that then you might think. Our guide to Primary Sources will help with getting started. Not to scare anyone off, but looking for primary documents does sometimes take you into corners of the library world you may not have been in before. Definitely ask us for help if you are at all unsure at any point about how to proceed. Not only can you ask questions of whoever happens to be at the reference desk, but you can schedule a research consultation if you want with one of our experience reference librarians, people who have many years experience of looking through all sorts of obscure and little visited parts of the library information landscape.