[WPF] Multilanguage application

Hi,
maybe this question is a replic of other questions present in this forum, but what is the best way for create an multilanguage app?

I'm following this tutorial, what do you think about this?

1) How can I set a default language in App.xaml
2) The method SetLanguageDictionary() should be inserted in each page or only in MainWindows.xaml?

You may report me a good guide or a tutorial?

Thanks.