Generally you should bury the deceased in a communal cemetery « cimetière communal », but a few exceptions exist. To do this you must meet several conditions that you'll find on this link :
In all cases, burial (as well as cremation / incineration) of a body must be authorized by the mayor.
In France it is prohibited to bury a body without a coffin « cercueil ».
The burial should take place between 24 hours and 6 days after the death.
If you do not have a gravesite (vault) « concession » « tombe » « caveau » you have to ask the opening
of a concession « ouverture d'une concession » in the city hall of the burial site.
If you organize the formalities by yourself, ask at the city hall of the burial site. If these formalities are taken care of by the funeral director's « pompes funèbres » they will organize everything for you.
In France, you can buy concessions for a period ranging from 10 to 99 years. In some communes, one can still find endless
Three months after the closure of the tomb, the family has an obligation to cover it with a stone. Then only, an ornamental stone may be installed.