For this i'd set up a variable based on your language and pass it through the URL.
i.e lang=something
call all your content in include files
include("".$REQUEST['lang']."contenttitle.php");
nameall content files like
$lang_contenttitle.php
so when you call the content just put the language variable in front of all calls. it will then display whatever language has been set.
this would even be easier just having all your content in a db.