Please be aware that citizens from certain countries may require a visa to enter France. If unsure, check with a French embassy or consulate.
Additional information can be found on the web site of the Ministry of Foreign Affairs:
In case you need an invitation letter, please contact Pierre Michaud at Cette adresse email est protégée contre les robots des spammeurs, vous devez activer Javascript pour la voir. . Please make sure you provide the postal address ("snail mail") where you want to receive the letter.