hello.html

<!DOCTYPE html>
<html>
  <head>
    <title>hello React</title>
    <meta charset="utf-8">
  </head>
  <body>
    <div id="app">
      <!-- my app renders here -->
   </div>
   <span> I'm adding a span tag underneath the div block </span>

    <script src="react/build/react.js"></script>
    <script src="react/build/react-dom.js"></script>
    <script src="main.js"></script>
  </body>
</html>