French people often have a lavish family meal at Christmas.
Starters could be for example oysters, shellfish or foie gras (may also be cooked into a main dish), or even escargots (snails in garlic butter) for those who like. The main course could be a nice piece of roastbeef, a goose, game meat, or a fine piece of red meat. It is very frequent that the menu will try to include something unusual, either expensive or original. The side serving would be greens and / or fruits, but nothing as ordinary as French fries or rice.
Adults could drink water, fine wine and Champagne , kids would have soft drinks or fruit juice.
Dessert would likely be a nice pastry, like the traditional "bûche de Noël", a log-shaped Christmas cake, or a Bavarois (a light fruit mousse).
The party and the meal itself are called "le réveillon" (the same name is used for New Year's eve party).
Joyeux Noël!
The primary Christmas decoration in France is the Christmas tree (or, in French, sapin de noel).
French Christians celebrate Christmas. French Jews celebrate Hanukkah.
In France, just like in America, if you are catholic then you do. 
There are no 'Christmas clothes' in France. People do just wear their regular winter clothing.
They eat crepes and other french food
French is the language of French people, who are the ones living in France.
Very few families in France are saying grace before eating. They don't do it much more at Christmas.
la France
People in France celebrate CHRISTMAS on December 6th
"la République Française", short form: la France
No one HAS to celebrate Christmas. Most French do.
People who live in France are know as French.