The whole navigation bar along with its JavaScript settings can be found here
http://jsfiddle.net/DyJzg/3/
right now it stays at the top of the page, but i am wo
if your element is 'nav' or your element class is '.nav' use this piece of css code:
nav, .nav{ position:fixed; top:0; width:your_custom_with; height: your_custom_height }
note: check this article of css positioning for more details: http://www.w3schools.com/css/css_positioning.asp