How easily set default language other than English ?

Hello friends,
I have one question about language options in the Elgg. Default language is English,  from basic administration, this can not change this(only in preferences of users). Is there any good and fast solution for this situation?
Thank you very much !
Beginning Developers

Beginning Developers

This space is for newcomers, who wish to build a new plugin or to customize an existing one to their liking