I want to publish a book-- help?

I'm a graduate student studying social studies education. I have a Bachelor of Arts in History, and I have noticed a lot of great stories in the study of history. I'd like to write either a historical fiction, or a fiction novel with inspiration from history. I've read that you should NOT write your book before just sending copies off to publishers. Do I contact a literary agent? Do I write a bit of my book and send that off? I'm super serious about pursuing this project as I get my M.Ed., but I've been in the world of academia too long, and know only how Historians get their academic works published.