Use the class .nav to create a navigation menu:

nav.nav-horizontal
	ul.nav-list
		li.nav-item
			a.nav-item-link...

You can easily integrate the dropdown component with navigation:

nav.nav-horizontal
	ul.nav-list
		li.nav-item.dropdown
			a.nav-item-link
			ul.dropdown-menu
				li.nav-item.dropdown-menu-item
					a.dropdown-menu-link.nav-item-link... // notice how navigation and dropdown classes are combined -- this is because they are both separate components

For vertical navigation, simply use the class .nav-vertical:

If responsive navigation is enabled, any .nav-horizontal navbars will turn to .nav-vertical navbars at the given breakpoint.

You can enable/disable responsive navigation by disabling the $navResponsive flag, and setting it to false