URL language strings

Hello guys , i wanna ask somethink about multi language blog/site on codeigniter.
Lets suppose was i run the site on domain.com  ok ? I have create 2 language files
under language folder with name us.php and gr.php. I want the default language
as greek. Also i have more than 10 fields , how can change the text with dynamic
language as $lang['main_header'] = "Header"; Must i create 2 diferrent views or exist
a way to do that ? Thanks sorry for my english syntax