Activating new languages in is very simple. Administrators can navigate to the Manage Languages area where they will be presented with a list of available languages. To activate a language and make it available in the Manage Translations area, simply click the tab so it becomes blue and says Enabled. 

If the language you require does not appear in the list contact

Once you have activated your new langauge you should proceed to the Managed Translations area and add all required translations.

For more information on adding and editing translations click here