modification image button to an external link

[OSC_FREAK]

I want to add an external link (example: http://www.host.com/newsletter/?p=subscribe&id=1) to my newsletter image button. What it the right modification? This is how my newsletter.php looks like in includes/boxes/:

 

<?php

?>

<!-- information //-->

<tr>

<td>

<?php

$info_box_contents = array();

$info_box_contents[] = array('align' => 'left',

'text' => 'Newsletter'

);

new infoBoxHeading($info_box_contents, false, false);

$info_box_contents = array();

$info_box_contents[] = array('align' => 'center',

'text' => tep_image_submit('subscribe.gif', BOX_HEADING_NEWSLETTER)');

new infoBox($info_box_contents);

?>

</td>

</tr>

<!-- information_eof //-->