Trying to add a class to a modal generated by a plugin when clicking an anchor

modal.js

        // I am using a prettyPhoto plugin for a modal
        //and I want to add a class to only certain modals by using only anchors with the .lower class as the trigger
        // How do I add a class to say... ('.pic_holder') after I have clicked on the trigger
        
        $("a.lower[rel^='prettyPhoto']").prettyPhoto({
            default_width: 480,
        });

// Found a solution, prettyPhoto had some callback functions. Just learning something new:

        $("a.lower[rel^='prettyPhoto']").prettyPhoto({
            default_width: 480,
      			changepicturecallback: function(){
      			  $('.pp_pic_holder').addClass('lower_video');
      			},
      			callback: function(){
      			  $('.pp_pic_holder').removeClass('lower_video');
      			}/* Called everytime an item is shown/changed */
        });