@jespah,
Actually the code to put in a background image is pretty basic. You can use the same code for either the whole page or for just a container like table or a div or a cell here is an example applying an image to the whole page
<body style="background-image;url(http://mysite.com/images/BG.png");background-repeat:no-repeat;background-aattachment;fixed;">
OK so basically you have to supply the path to the image you want to use i have used an absolute path here i.e. "http://etc". BTW, paths can be troublesome if you don't get the path or syntax just exactly right then it won't find the image. Also in my example i made the image (background) fixed so the page scrolls and the background stays fixed