External Login Page

[Rag3]

I have an external login page called index.html my login is in a form on my navbar.

Here's the code

<li class="dropdown"><a class="dropdown-toggle" id="dLabel" role="button" data-toggle="dropdown" data-target="#" href="../../page.html">
   Login<strong class="caret"></strong></a>
<ul class="dropdown-menu" role="menu" aria-labelledby="dLabel"><!-- login form -->
<form action="http://www.07-pk.com/forum/login.php" method="post" onsubmit="md5hash(vb_login_password,vb_login_md5password,vb_login_md5password_utf)">
<script type="text/javascript" src="../../forum/clientscript/vbulletin_md5.js"></script>
		Username: <input type="text" class="button" name="vb_login_username" id="navbar_username" size="10" accesskey="u" tabindex="1" value="Username" onfocus="if (this.value == 'Username') this.value = '';" /><br />
		Password: <input type="password" class="button" name="vb_login_password" size="10" accesskey="p" tabindex="2" /><input type="submit" class="button" value="Login" tabindex="4" title="" accesskey="s" /><input type="hidden" name="s" value="" /><input type="hidden" name="do" value="login" /><input type="hidden" name="forceredirect" value="1" />			<input type="hidden" name="vb_login_md5password" /><input type="hidden" name="vb_login_md5password_utf" /><input type="hidden" name="url" value="http://www.07-pk.com/forum/" /></form><!-- / login form -->

It just re-directs to the forum.php with the user logged in. How would I go about showing the user logged in on my index.html in my navbar instead of it just showing the input fields to login. I want it to say Welcome, Spencer. Or something that shows you're logged in on my index.html.