We don’t recommend to edit original theme files.
You’d better create child theme or write style modifications in the file custom.css.
How to create custom.css you can watch in this tutorial (it’s for Legenda theme but the process is the same).
If you’re going to create multilingual site you need use WPML plugin http://wpml.org/ and you’ll be able to replace current languages with the flags adding wpml widget in “Place in header top bar” area in Appearance > Widgets.
