Function for Main nav menu

Hello again, sorry for all these questions, but I like sooo much your theme and I’d like to enrich it with little details to make it perfect for my company 🙂 🙂

I copied a function in the Functionality plugin editor, as hannah suggested, but it’s not working. I used it with the theme Graphene, here it is:

function my_custom_menu_item( $items, $args ) {
    if ( function_exists ( 'the_msls' ) && 'Header Menu' == $args->theme_location ) {
        $obj = new MslsOutput;
        $arr = $obj->get( 2 );
        if ( !empty( $arr ) ) {
            $items .= '<li>' . implode( '</li><li>', $arr ) . '</li>';
        }
    }

    return $items;
}
add_filter( 'wp_nav_menu_items', 'my_custom_menu_item', 10, 2 );

A flag should display on the right of my Main nav menu ( http://www.spinips.com ) and allows to skip to the translation of the visited page ( http://www.spinips.com/en – I still need to change theme there, but you can see a widget with languages at the bottom of the home page)

May you help me someway? Thank you!!