To get automatic language selection, you must tell your web browser what your preferred language is. How you can do that depends on the browser you are using.
Edit -> Preferences -> General -> Languages
Tools -> Options -> General -> LanguagesIn older version you have to go to about:config and change the value of intl.accept_languages.
Edit -> Preferences -> Navigator -> LanguagesNote: with Netscape 4.x you need to make sure you select the language from the available choices. A number of people reported problems because they typed in the language by hand.
Tools (or View or Extras) -> Internet Options -> (General) Languages
Edit -> Preferences -> Web Browser -> Language/Fonts