How to add image dynamically?

[Gavan]

I am very new to web development and PHP. May be this is simple question but searched a lot in Internet but couldn't find the solution.I have this code in my CSS:\[code\].categories .cat_sec { float: left; width: 232px; height: 360px; padding-top: 10px; margin-right: 1px;}.categories .cat_sec h5 { width: 232px; color: #FFF; padding: 10px 0px;}.categories .cat_sec .cats { width: 232px; height: 50px; background-repeat: no-repeat; padding-top: 259px;}.categories .cat_sec .cat1 { background-image: url(../images/gold/bangles.gif);}\[/code\]And calling this CSS style in HTML by the following way:\[code\]<div class="cat_sec"> <h5> <?php echo $mCollections_array['SubCollectionName']; ?></h5> <div class="cats cat1"> <ul> <li><a href="http://stackoverflow.com/questions/14414102/listing.php">Some Text </a></li> <li><a href="http://stackoverflow.com/questions/14414102/listing.php">SomeText</a></li> <li class="viewall"><a href="http://stackoverflow.com/questions/14414102/listing.php">View All</a></li> </ul> </div></div> \[/code\]I have to change the image dynamically from the server. But i couldn't get any idea about changing the image in this line of code \[code\]<div class="cats cat1">\[/code\]. In this \[code\]cat1\[/code\] represents the image already defined.How do I add the image dynamically in the above code?