index.html

<!DOCTYPE html>
<html>
<head>
  <title></title>
  <script src="https://cdn.firebase.com/js/client/2.3.2/firebase.js"></script>
  <script type="text/javascript" src="app.js"></script>
</head>
<body>

<h2>Messages</h2>
<div id="messages">
  
</div>

<hr>

<form id="form">
   From: <input type="text" id="fromUser"> <br>
   To: <input type="text" id="toUser"> <br>
   <textarea id="msgText"></textarea> <br>
   <input type="submit" value="Send">
 
</form>

</body>
</html>