It might be a none theme related question (I am not sure thought). I am trying to change the language of the comment on a blog. The "Submit" button is in english (it should say "Soumettre" in French) and the error message "Please fill the field." is also in english instead of french.
I added some code in the wp-config.php but it did not change anything.
How can I do this? You can see it at the bottom this page for example: