Include the script and the stylesheet
Add the attribute "parallax-bg" to the element that should be the background of its parent. It will be absolute positionized
<div class=u1-parallax-bg-stage>
<parallax-bg style="background-image:url(bg.jpg)"></u1-parallax-bg>
other content
</div>
The stylesheet and the "parallax-bg-stage" attribute on the parent are optional but recommended