Try this:
<html>
<head>
<title>{$mybb->settings['bbname']} - {$lang->registration}</title>
{$headerinclude}
<script type="text/javascript" src="jscripts/validator.js"></script>
</head>
<body onload=' location.href="#content" '>
{$header}
<div align="center">
<a name="signup"></a>
<form action="member.php" method="post" id="registration_form" name="registration_form"><input type="text" style="visibility: hidden;" value="" name="regcheck1" /><input type="text" style="visibility: hidden;" value="true" name="regcheck2" />
{$regerrors}
<table border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="30%" valign="top">
<div class="insetbox" style="
border: 1px solid #DEDEDE;
margin-left: 20px;
margin-top: -10px;
">
<h2>Sign Up ↓</h2><br />
<table cellspacing="0" cellpadding="4" width="95%">
<tr>
<td colspan="2">
<h4>Username</h4>
<input type="text" class="textbox" name="username" id="username" style="width: 100%; padding: 3px; font-size: 1.2em;" value="{$username}" /></td>
</tr>
{$passboxes}
<tr>
<td><h5>Email</h5>
<input type="text" class="textbox" name="email" id="email" style="width: 100%; padding: 3px;" maxlength="50" value="{$email}" /></td>
<td><h5>Confirm Email</h5>
<input type="text" class="textbox" name="email2" id="email2"style="width: 100%; padding: 3px;" maxlength="50" value="{$email2}" /></td>
</tr>
<tr>
<td colspan="2" style="display: none;" id="email_status"> </td>
</tr>
</tr>
</tbody></table>
<input type="hidden" name="step" value="registration" />
<input type="hidden" name="action" value="do_register" />
<br />
<h4 style="text-align: center;">Important Stuff</h4>
<p class="smalltext">By joining our forum, you agree to our <a href="http://harajuju.net/misc.php?action=help&hid=8" target="_blank">Community Rules</a> and <a href="http://harajuju.net/misc.php?action=help&hid=13" target="_blank">Terms of Service</a>.</p>
<input type="submit" class="button" style="font-size: 1.5em; margin-left: auto; margin-right: auto; width: 100%;" name="regsubmit" value="Let's do it" />
</div>
</td>
<td width="70%" valign="top" style="padding-left: 40px;">
<br class="clear">
</td>
</tr>
</table>
<br />
<div align="center">
<input type="hidden" name="step" value="registration" />
<input type="hidden" name="action" value="do_register" />
</div>
</form>
<script type="text/javascript">
<!--
regValidator = new FormValidator('registration_form');
regValidator.register('username', 'notEmpty', {failure_message:'{$lang->js_validator_no_username}'});
regValidator.register('email', 'regexp', {match_field:'email2', regexp:'^([a-zA-Z0-9_\\.\\+\\-])+\\@(([a-zA-Z0-9\\-])+\\.)+([a-zA-Z0-9]{2,4})+$', failure_message:'{$lang->js_validator_invalid_email}'});
regValidator.register('email2', 'matches', {match_field:'email', status_field:'email_status', failure_message:'{$lang->js_validator_email_match}'});
{$validator_extra}
regValidator.register('username', 'ajax', {url:'xmlhttp.php?action=username_availability', loading_message:'{$lang->js_validator_checking_username}'}); // needs to be last
// -->
</script>
<!-- <script type="text/javascript" language="JavaScript">
document.forms['registration_form'].elements['username'].focus();
</script>
-->
</div>
{$footer}
</body>
</html>
