register_nav_menus( $locations );
function register_multiple_menus() {
register_nav_menus( array(
'menu_three' => 'Menu Name',
'menu_four' => 'Menu Name',
'menu_five' => 'Menu Name',
'menu_six' => 'Menu Name'
) );
add_action( 'init', 'register_multiple_menus' );
add_action( 'genesis_after_header', 'add_third_nav' );
function add_third_nav() {
wp_nav_menu( array(
'theme_location' => 'third-menu',
'container_class' => 'genesis-nav-menu' ) );
}