Features / Usability

Hello everybody !

My 1.9 wiki web site is running pretty well on a windows/easyphp LAN.
BUT, when i want to change the language of the website, i go as admin to admin->general and change the language to french...and nothing happens,i don't want to rebuid my website from the scratch...
So , I will reinstall an empty french tikki and use export from the old database toward the new one. What table should i export for :
- all my wiki pages
- the personnal menu i've build
- the features enabled/disabled
- all users

Thanks a lot to everyone who can help me
wani