jquery function in static site

Hey,

I´ve found out, that the more-tag is only working in articles but not in sites - is that right?

If so, i´d like to use this funktion:

$('#more').click(function() {
    jQuery(this).text('less about us');
    if($('#extra').is(':visible')){
          jQuery(this).text('Less about us');
    }else{
          jQuery(this).text('More about us');
    }
    $('#extra').slideToggle('fast');
    return false;
});

to hide/show html elements

<a href="#" id="more">More about us</a>
<div id="extra">ghjjkkhjhg</div>