That image is stored under the images folder and it is called: storeMessage_bg.png.
If you wanted to change some of the CSS Properties, you can do that in the home.css file which is located under the css folder.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.