Edit in JSFiddle

$(document).ready(function() {
    $('#tabs').tabs({
        selected: 0,
        fx: {
            opacity: 'toggle',
            duration: 200
        }
    });
});

<div id="tabs">
  <ul>
    <li><a href="#tabs1">tab1</a></li>
    <li><a href="#tabs2">tab2</a></li>
    <li><a href="#tabs3">tab3</a></li>
  </ul>
        <div>
            <div id="tabs1">tab1tab1tab1tab1tab1tab1</div>
            <div id="tabs2">tab2tab2tab2tab2tab2tab2</div>
            <div id="tabs3">tab3tab3tab3tab3tab3tab3</div>
        </div>
</div>