This code shows how to add an event to a click or other user event.

ga_event.js

$('.tab').click(function() {
  $(this).show();
  var eventCategory = jQuery(this).attr('data-category');
  var eventAction = jQuery(this).attr('data-action');
  var eventLabel = window.document.title;
  _gaq.push(['_trackEvent', eventCategory, eventAction, eventLabel]);
});