So I made my webpage in photoshop.
Sliced it all up.
And coded it so it isn't a huge image its just a couple images and a bunch of really small file size background images.
My page is like 800 pixels wide.
How do I go about re-coding it so that it stretches to fit like a 1240 pixel wide screen ?
Is you want a variable width of your site, you cannot use fixed images for your style. You need to have at least some images that can be repeated to fit the size. So for example a design like this:
Fixed width left side - variable width middle part with image to repeat - fixed width right side
You can still have images for logos etc.