In the main body of the page, add sections with IDs that match the links in your side bar: eg Section 1
That's it!
EDIT
How do I get it to style like the Bootstrap example on their site though?
Here's a variation if you want stying similar to the bootstrap page
http://jsfiddle.net/panchroma/ExWDq/
You will see that I've changed the classes on the nav list ul to make better use of some built in Bootstap styling, I've added chevrons to the menu links, and added styling and media queries for the nav list.