Script for picture to fit to screen size

I run a clan for a game and need to make a splash screen and need a script so it will fit to the screens size for players with different screen settings, please can some one help me out with a script.

You could try something like this -

<div id="background">
<img src="yourpicture.jpg" alt="">
</div>

CSS -

body, html, #background, #background img {
margin: 0;
padding: 0;
width: 100%;
height: 100%;
}

That will stretch your image, although I can't imagine it being very pretty at high resolutions...