Go to:   /templates/crystal/css/wrappers.css

scroll down a little bit and find this section.

.toparea_ajax {
    font-family: 'Trebuchet MS', Arial, Tahoma, sans-serif;
    font-size: 13px;
    font-style: italic;
    font-weight: bold;
    background-image: url(../images/bg_toparea_mo.png); (here is your link over menu image you see in video)
    background-repeat: no-repeat;
    color: #666;
    width: 700px;
    height: 40px;
    padding-top: 5px;
    text-align: center;
    cursor: crosshair;
}

Now replace with your own image.

Video Here