First of all install Native dashboard @ https://www.ads-software.com/plugins/wp-native-dashboard/
(it might say is not tested on your WP version. But it works fine on my 4.4 version of WordPress)
Than this will give you all the available language option for for your back end admin area.
When you go back to your User language Switch setup section, You will see all available language.
But How to translate each page for particular language is a mystery for me and Looking for answer too.
Good luck.
