create a div around all your content, give it a border value and color, then create a div inside that and set the background color to whatever color you want.
Border fullscreen? meaning you want it at the edge of the browser window, no matter the size/resolution? Off the top of my head try adding a border style to the body (CSS).
Example
HTML:
body {
border:solid 1px #ddd; /* YOUR BORDER */
background-color: #eee; /* YOUR BACKGROUND COLOR */
}