widgetkit spotlight

Hi,
I am trying to use the “spotlight” widget of “Yootheme widgetkit” and apparently it needs some HTML code involvement and I can’t figure out where to put it (file, location), and how to use it in my site. can you help?
below is the short instruction I found on the official website:

“
How To Use

Use the HTML5 custom data attribute data-spotlight to activate the spotlight.

<img src=”/image.jpg” width=”180″ height=”120″ alt=”” />

To create a custom overlay use a div element with the CSS class overlay. You can set the effect parameter to the data attribute. For example:

<img src=”/image.jpg” width=”180″ height=”120″ alt=”” />
<div class=”overlay”>Custom Overlay</div>

You can set the effect parameter to fade, bottom, top, right and left.
“

thx.