1. Online addic7ed translation feature.
You have to log into the site, look after what episode you want to translate, then, after you'll press the "join translation" button (or, in case there is no translation started, select "Start translation" button, select language for translation and start to do what you can to do ).
I advice you to read carefuly the Translation Rules (you can read these when you "join" an already open translation).
2. A software for editing / translating subtitles like Subtitle Edit or Subtitle Workshop or whatever. That means you'll work ''off-line".
We have there a French subforum, and a lot of some good translators, search and read through that subforum.
We have here a French Subforum where you can discuss in your language with some of French addic7ed's users.
For any informations about working to any translations, you should contact prinzeza, jpdom, marineemma, rumdiggie, they are those who are tying to put some order in this French translation work.