Register 4 Menus

Main navigation plus 3 extra menus.

if ( ! function_exists( 'cm_custom_navigation_menus' ) ) {

// Register Navigation Menus
function cm_custom_navigation_menus() {

	$locations = array(
		'Main Navigation' => __( 'The main navigation for the site', 'text_domain' ),
		'Menu2' => __( '', 'text_domain' ),
		'Menu3' => __( '', 'text_domain' ),
		'Menu4' => __( '', 'text_domain' ),
	);
	register_nav_menus( $locations );

}

// Hook into the 'init' action
add_action( 'init', 'cm_custom_navigation_menus' );

}