It’s always good to start with a wide view, encompassing a bit of history, a bunch of geography, and some cultural context.
Good online/downloadable maps of French wine regions
More links for learning
WineSearcher: French wine
Wine Cellar Insider: Overview of French Wine Law and AOCs
SommWine: The beginning of French Wine Law (good article for background info)
Wine Searcher: French Wine Label Information
Wine Spectator: “Terroir,” defined
Wine and War: This is a must-own book for history buffs, covering the stories of WWII and the impact on the French wine industry. There are some AMAZING stories to be found in this book, and I really wish it was turned into a movie! Note that it’s easy to find used copies: check Ebay or Abebooks online.