I am trying to add a social bookmarking site to a sidebox. Here is my homepage: http://www.lasilhouettelingerie.com/store/ (Please look in the top right corner at the Social Bookmarking sidebox).

Here is the code where I am supposed to paste my add this code into this sidebox:

Code:
$content = '<div id="absolutelinksContent" class="sideBoxContent centeredContent">';

/* Your html and/or javascript code goes between the 2 single quotes in the next line */
$content .= '<!-- AddThis Button BEGIN -->
<script type="text/javascript">var addthis_pub  = "MYUSERNAMEHERE";</script>
<a href="http://www.addthis.com/bookmark.php" onmouseover="return addthis_open(this, '', '[URL]', '[TITLE]')" onmouseout="addthis_close()" onclick="return addthis_sendto()"><img src="http://s7.addthis.com/button1-bm.gif" width="125" height="16" border="0" alt="" /></a><script type="text/javascript" src="http://s7.addthis.com/js/152/addthis_widget.js"></script>
<!-- AddThis Button END -->';

$content .= '</div>';

?>
According the the instructions I can paste html or javascript in between the single quoate of the $content'' line which is what I did. The code has errors (the page goes blank below this sidebox when I use the code above. Is the code syntax wrong? Anyone know how I can make this work? I am guessing it has to do with the single double quotes but I don't quite understand .php language.