Help with WP Background Image

[mcwb201]

I am building a wordpress site and I have been able to customise a theme to use my own graphics. However, I have added a background image but don't know how to ensure it stays in a certain position instead of moving with the width of the page.

My code:

body {
	margin: 0;
	background: #780e00 url("images/splatter1.png") no-repeat;
}

I have it no-repeat but don't know how to fix its position. Once I know how to I can play around with the size of the image to ensure its placed where I want it.

Please help!

I can provide more details if needed..!

THANKS

M