Adding a new SECOND background to My page!

Hi ppl, I want to make a theme that uses two backgrounds, like you can see on this one here:
http://www.emineer.com

So I made similar template, whit this code:

body {
font-size: 62.5%;
font-family: 'Lucida Grande', Verdana, Arial, Sans-Serif;
background: #d9d9d9 url('images/bg.jpg') center top no-repeat;
color: #black;
text-align: center;
}
user agent stylesheet
body {
display: block;
margin: 8px;
}

and it shows that background on top, when I put another image in background code “bg1” instead of “bg” and put “center bottom” it also works, BUT, I want to have both images into this page, can someone please help, what is most simple way to do it?!?!