goto url

Between the div tags is the error message, what is showed a new page.
I would like to set an url instead of div’s content. How to solve this problem? Thx

The code is…

<?php

global $wpdb;

if ($_GET['subscribed'] == "true")
{
        require "templates/confirm_subscription.html";
        exit;
}

function error($error)
{

        ?>

<div style="font-family: Arial">
  <h2 align="center">An Error Has Occured</h2>
  <div align="center">
    <div style="width: 400px; padding: 10px; text-align: left; background-color: #336699; color: #fff; font-weight:bold; font-family: Arial; border: 1px solid #ccc;"> <?php echo $error ?> </div>
    <a href="javascript:window.history.go(-1);">Click Here To Go Back</a> </div>
</div>
<?php
        wp_credits();
        exit;

}