I can't access the Toolbar

I wrote some code in Cesium Sandcastle that uses the toolbar to have buttons with various functionality. I tried to then transfer that code into an HTML and Javascript file to run on my own web server. The code that doesn't use the toolbar works, which means I downloaded all the right things and the system is working, but the part that relies on the toolbar does not work. That means I probably defined the toolbar wrong in the HTML file, but I don't know what I did wrong. Here is the basic HelloWorld example slightly modified.

<!DOCTYPE html>
<html lang="en">
  <!-- Use correct character set. -->
  <meta charset="utf-8">
  <!-- Tell IE to use the latest, best version. -->
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <!-- Make the application on mobile take up the full browser screen and disable user scaling. -->
  <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, minimum-scale=1, user-scalable=no">
  <title>Hello World!</title>
  <script src="../Build/Cesium/Cesium.js"></script>
      @import url(../Build/Cesium/Widgets/widgets.css);
      html, body, #cesiumContainer {
          width: 100%; height: 100%; margin: 0; padding: 0; overflow: hidden;
    @import url(../templates/bucket.css);
  <div id="cesiumContainer"></div>
  <div id="cesiumContainer" class="fullSize"></div>
  <div id="loadingOverlay"><h1>Loading...</h1></div>
  <div id="toolbar"></div>
      **Javascript code here**
     var toolbar = document.getElementById('toolbar');
     **Javascript code here**


Any help is greatly appreciated. Thank you.