The first place to look for information about your author is the book itself.
Be sure to look at the front cover and the back cover on the inside and outside. You may have missed a page that says "about the author". It also could be hidden in the introduction to the book. You don't necessarily need the author's life story as much as you need to find a few facts.
1. Check the author's name in the GIL Catalog of Books and the GIL Universal (University System Catalog). This will tell you if the author wrote other books. Knowing that the author wrote other works adds to your information about his or her credentials as an author.
2. Try searching the author's name at Amazon.com. This will may also provide information about your book and to identify other books by your author.
3. Try searching the author's name on www.google.com. If your author may have a web-page. Many historians are college professors and may have extensive information listed at thier college website. If your book is fairly new and it says "Author Bob Smith is a Professor at the Harvard University" that's a really great clue. Try searching him on google using terms like "Bob Smith and Harvard".