If you were modifying the admin bar in WordPress 3.x you used to call this:

// Add a link to the dashboard in the [pre-existing] site-name node
$wp_admin_bar->add_menu( array(
	'parent' => 'site-name',
	'id'     => 'dashboard',
	'title'  => 'Dashboard',
	'href'   => admin_url(),
) );

to add a new item to your admin toolbar. Now you just replace add_menu with add_node – they have exactly the same effect – and exactly the same syntax – just a slightly different semantic effect on the reader.