That site has basically 2 images top and bottom with a standard color in between.
You really should create your own images...
When you have them you can apply them through the stylesheet kinda like the following and make adjustments to match your images:
Code:
.leftBoxHeading, .rightBoxHeading {
margin: 0em;
background-color: transparent;
background-image: url(../images/your_image.gif);
padding: 0.5em 0.2em;
}
and
.sideBoxContent {
padding: 0.4em;
border-left: 1px solid #9B11A1;
border-right: 1px solid #9B11A1;
padding-bottom: 2.5em;
background-color: #ffffff;
background-image: url(../images/sidebox_bot.gif);
background-repeat: no-repeat;
background-position: 0% 100%;
}