I am working on a Wordpress Theme, I need to work on the navigation, I am having a little trouble creating it.

The navigation I am looking for looks like this: www.neu.edu/humanities.

I have gotten this far:

if (is_front_page()) {
  wp_list_pages('title_li=&exclude=12&depth=1');
}
else {
  // display the subpages of the current page while 
  // display all of the main pages and all of the 
  // and display the parent pages while on the subpages
}