cant get the inner body container to float center when image is changed to css

Hi, all. I havnt done any css for a while so bear with me!

I'm trying to change the use of a image which is repeated

repeat-y 50% 0

the page is supposed to be 960px wide, with shadow and floating center.

so instead of the image i wanted to use css, everytime I change the width, it wont float center, but I need to difine the width somehow else it covers the whole body.

here is what Ive got...It's a bit messy...

/*.bg1{background:url(../images/shadow-bg.png) repeat-y 50% 0}*/
.bg1{background:#fff; width:960px; alignment-adjust:middle;-moz-box-shadow: 3px 3px 4px #CCC;

-webkit-box-shadow: 3px 3px 4px #CCC;

box-shadow: 3px 3px 4px #CCC;

/* For IE 8 */
-ms-filter: "progid:DXImageTransform.Microsoft.Shadow(Strength=4, Direction=135, Color='#CCCCCC')";

/* For IE 5.5 - 7 */
filter: progid:DXImageTransform.Microsoft.Shadow(Strength=4, Direction=135, Color='#CCCCCC');}

PLEASE HELP! Thanks!!!