Divs normally go onto a new line, so if you code three divs, they should be on top of one another. Make sure they have no top or bottom margins or padding.
<div id="top"> </div>
<div id="middle"><p>Content here</p></div>
<div id="bottom"> </div>
CSS something like:-
#top, #middle, #bottom { margin: 0; padding: 0; }
#top { background-image: url(top.jpg); width: ??px; height: ??px; }
#middle { width: ??px; }
#bottom { background-image: url(bottom.jpg); width: ??px; height: ??px; }
This assumes that the top.jpg and bottom.jpg have a fixed width and rounded corners (one is normally the other saved upside down).
Quite often a containing div is created around all three divs so that the containing div can be accurately positioned and hold together the inner divs.
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.