tabs css

hi,
i'm rolling my own tabs (because i need them to added dynamically,
and don't need the containers) and was trying to get the look and feel
of jquery's tabs.
i tried:
<ul class='ui-tabs-nav'><li class=''><a href=''><span>test</span></a></
li></ul>
and included ui.tabs.css, but it didn't do anything - the ul was
displayed as a regular list
any suggestions?
thanks