Tooltip for Image Hover?

Ok I run a game site that contains lots of flash games, well I came across this site. www.CrapVille.com

If you hover over the thumbnail's in the middle a box appears with a description in it. That's exactly what I wanna do with my thumbnails and still keep it's hover properties without losing them.

So basically just like that CrapVille site, is anyone familiar with this and how would I do this.

 

Upon viewing the page's source code (right click and select View Source), it looks like they're using CSS.

<img src="http://www.crapville.com/thumbs_videos/newsbloopers.gif" alt="" width="75" height="75" border="0" title="offsetx=[10] offsety=[10] header=[&lt;font class='tooltiptitle'&gt;News Bloopers:&lt;/font&gt;&lt;br&gt;A small collection of news bloopers from around the world. Pretty funny stuff] body=[]" class="graphic"><br>

Code (markup):

(notice the class='tooltoptitle')

And the CSS in the beginning of the document is:

<style type="text/css">

.tooltiptitle {
	font-size: 11px;
	font-family: Arial, Helvetica, sans-serif;
	font-weight: bold;
	color: #FFFFCC;
	text-transform: uppercase;
}
.tooltipdescription {	
	font-size: 10px;
	font-family: Arial, Helvetica, sans-serif;
	font-weight: normal;
	color: #76AAD1;
}
-->

</style>

Code (markup):

 

The thumbnails look to be using title tags, title="tool tip content here".

Since you are talking about images, alt="content" allows visually impaired visitors with Screen Readers to decipher your images. I use both alt and title together, usually.

CSS seems to be geared towards controlling the tooltips font and color.