<div id="movable">
    <p>Hello</p>
</div>

<a id="move_box" href="#">Move box</a>

#movable {
    background-color: blue;
    height: 15px;
    weight: 15px;
    color: white
}

    $('move_box').addEvent('click', function(event) {
                    event.stop();
                    new Fx.Move('movable', {
                        offset: {x: 50, y: 50}
                    }).start();
                });