CSS Popup Window

Hi guys, I need to replace my old IFRAME popup window with the new style. Original popup can be seen here: [login to view URL] When I click on Add button an iframe shows up with information containing quantity and item number added to Shopping Cart. I need to replace this ugly iframe with new style popup window like this one here: [login to view URL] The script is free and can be downloaded. FTP access will be granted. I need this quick and clean. Compatible with any most popular browsers. Make sure Add button has only onclick function and all .js and .css connect apart. Thanks on a button when a web site visitor clicks on Add to Cart button. Right now it is showing an ugly and I need to replace it with good looking and clean Popup window.