setting margins

[reciecup]

How do I set the margin size of the left and right side of my website.

Right now my settings look like this:

 

BODY {

background: #000000;

color: #ffffff;

background-image: url(/images/rc_background.gif);

background-repeat: no-repeat;

margin-left: auto;

margin-right: auto;

margin: 90px;

}

 

But when I set the margin to 90px, it shrinks my whole site ( top, bottom, left and right side )

I only want to change the left and right side. How is this done? My site is RenderCandy to get an idea of what I'm talking about.

 

 

Thanks

[reciecup]

Please...I really need help with this...does anyone have any suggestions????? :'( :(