Load page into DIV with Ajax

I’m really a noob when it comes to WordPress, right now I’m working on a theme that basically is all static, if you want to edit something you’ll have to edit the .php file than rather doing it on the admin. It is a landing page where you click a menu button and a modal appears with the content, to do this I followed this tutorial which is not exactly WordPress-oriented. I’m loading static pages via ajax and I really want to change this to editable WordPress pages but I have no idea how to do it. I don’t post the code because everything is like in the tutorial, I haven’t used functions.php or anything. How would you call the content of a page to load as if it was a static page just like in that tutorial?

The ajax call

$(function() {
        $('.w-container .w-nav-menu a').click(function() {
            var $linkClicked = $(this).attr('href');
            var $pageRoot = $linkClicked.replace('#', '');
            if (!$(this).hasClass("active")) {
                $(".w-container .w-nav-menu a").removeClass("active");
                $(this).addClass("active");
                $.ajax({
                    type: "POST",
                    url: "./wp-content/themes/THEMENAME/load.php",
                    data: 'page='+$pageRoot,
                    dataType: "html",
                    beforeSend: function(){
                            $('#canvasloader-container.wrapper').show();
                        },
                    complete: function(){
                            $('#canvasloader-container.wrapper').hide();
                        },
                    success: function(msg){
                        if((msg))
                        {
                            $('.content').html(msg);
                            $('.content').hide().fadeIn();
                        }
                    }
                });
            }
        event.preventDefault();
    });

    var hash = window.location.hash;
    hash = hash.replace(/^#/, '');
    switch (hash) {
        case 'products' :
            $("#" + hash + "-link").trigger("click");
            break;
        case 'about' :
            $("#" + hash + "-link").trigger("click");
            break;
        case 'storelocator' :
            $("#" + hash + "-link").trigger("click");
            break;
        case 'media' :
            $("#" + hash + "-link").trigger("click");
            break;
        case 'faq' :
            $("#" + hash + "-link").trigger("click");
            break;
        case 'contact' :
            $("#" + hash + "-link").trigger("click");
            break;
        }
    });

load.php

<?php
    if($_POST['page']);
    $page = $_POST['page'];
    if(file_exists('pages/'.$page.'.php'))
    echo file_get_contents('pages/'.$page.'.php');
    else echo 'Unavailable';
    ?>

I have only found tutorials with posts and that stuff, and that’s not what I want.

I’m new to this forum so if I’m posting on the incorrect section, please, move it

[ No bumping please. ]