A quick overview is available below. You can view flexMenu on GitHub to get more details and grab a copy of the plugin.
!important: Make sure you add class "selected" on the first 'li' and class "active" on the first anchor tag for the menu active states to worked. See example directory.
<ul class="flex">
<li class="selected"><a class="active" href="page.html">Menu Item</a></li>
<!-- more list items... -->
</ul>
$('ul.flex').flexMenu();