Simply and essential code to use .mo files as multilanguage system.
You can find the .pot file as template, more informationatrion regarding how made .pot file here.
##how it works
It' work by get language international code by get variable like that
example.php?locale=it_IT
in page use the syntax
<?php echo(__('hello world')); ?>
with bouble underscore __ as funtion prefix.