Doctors certificate + permit de chasse or membership of a target club & naturally secure storage (your chosen gunsmith / retailer will advise).
I was told there is an exam, but from this article, that would only apply for hunting. http://www.thetruthaboutguns.com/2015/01/daniel-zimmerman/mon-dieu-a-review-of-french-gun-laws/
However, from this article http://www.thehuntinglife.com/forums/topic/300853-changes-to-french-gun-laws/ (scroll down a few posts) it would appear that you don't need one for your own land.
Go to www.service-public.fr and put armes de chasse in the search box and it gives lots of info