Help getting jscalendar working

I'm new to php/javascript so I don't really understand how to do this. I want to add a pop-up calendar to an input form on a drupal page. I have written the form in html with php commands to $_POST the values from the form to a database. Now I just want to add the calendar to the text box for dates.

e.g.

I tried adding the code as described in the readme file to my page:

  $form['date'] = array(
    '#type' => 'textfield',
    '#attributes' => array('class' => 'jscalendar')
  );

I also tried adding class='jscalendar' to my form tag but that doesn't change anything either. Clearly there is more to it. Could someone please provide an example of a page with a form on it that uses jscalendar popups?

[ jstools module is uploaded and jstools and jscalendar are enabled. Drupal version 4.7.3. Downloaded jstools today. ]

thanks
Bill.