I'm attempting to write a bit of code that will let me change images or perhaps a whole block of the div with respect to the language

    if($_SESSION['lang'] == "fr"){
            echo "images/header-fr-4.jpg";
    echo "images/header-4-en.jpg";

Can there be every other method of carrying this out in wordpress?

The Gengo wordpress plugin for WordPress supports converted posts and pages, in addition to template elements based on language. http://wordpress.org/extend/plugins/gengo/

For instance:

<?php if (islanguage('en')) echo "You are reading in English"; elseif (islanguage('ja')) echo "You are reading in Japanese"; else echo "You are seeing all posts..."; ?>

You could do this something similar to this:

$lang = $_SESSION['lang']


echo "images/header-4-".$lang.".digital"

You can always sanitize the variable within the header so you could utilize it through the entire script.