I'm trying to get my myspace background to be stretched across the page....but it keeps tiling

i want one pic for the background i don't want it tiled i want it fixed but what size does the pic need to be for it to stretch across the screen?

I'm trying to get my myspace background to be stretched across the page....but it keeps tiling itself. HELP!

{Background Settings}

body {

background-image:url("YOUR PIC URL");

background-repeat:no repeat;

background-position:center;

background-attachment:fixed;}

The "no repeat" is the part that is important to keep it from tiling.