[jQuery] superfish menu on beez

[liku]

I have started to use joomla 1.5 and I would like to change manu and
start using superfish. I adde css na javascript link to index.php and
now I do no know what to do next. When I insert his code:

  <script type="text/javascript">

    $(document).ready(function(){
        $("ul.sf-menu").superfish();
    });

</script>

to index.php it does not work. Please could anyone help me how to
start to use that menu (where to put initialize code?).
Thanks
Libor