reference http://api.jqueryui.com/tabs/#option-active
$( "#tabs" ).tabs({ active: 1 });
your html like
<div id="tabs">
<ul>
<li><a href="#tabs-1">Nunc tincidunt</a></li>
<li><a href="#tabs-2">Proin dolor</a></li>
<li><a href="#tabs-3">Aenean lacinia</a></li>
</ul>
<div id="tabs-1">
<p>Some content.</p>
</div>
<div id="tabs-2">
<p>Some content.</p>
</div>
<div id="tabs-3">
<p>Some content.</p>
</div>
</div>