Hi duch,
anyone, please correct me if I'm wrong here...but from what I understand and also what I have experienced, the localization is done automatically depending on what your browser returns as a preferred interface language when loading the page.
you can easily check this by running the following javascript code:
var userLang = window.navigator.userLanguage || window.navigator.language;
alert("my locale language is: "+userLang);
If this returns something like "en-US" then the display will be set to English.
For French it most likely has to be something starting with "fr".
So, in this case you need to change the preferences of your browser to display the right interface language. For more info google for "set navigator.language" or take a look at this example:
http://www.wikihow.com/Change-Your-Browser%27s-Language.
Best,
jan