Hi

Somewhere I wrote a reply to a similar question - I have a French ancestor + believe me it is a challenge. No centralised registration system, no censuses, just a similar system to the system running in England + Wales before 1837 - parish records. These should have been raised in duplicate + 1 sent to the head town of the departement but didn't always happen. Basically if you don't know where the event took place +/or you don't know where the birth/marriage took place then there's no magic fix.
Googling brings up contacts - I'd follow those for a start. If he was born in France + you know the date + place of birth then with a bit of luck the date of marriage + death might be in the margin.
You could do what I did - brush up your French + join French groups??