functions.php

/**
 * Register our sectional titles in the customizer
 * @param class $wp_customize Instance of WP_Customize_Manager created when using the 'customize_register' hook
 */
add_action( 'customize_register', 'jn_customizer_titles' );
function jn_customizer_titles( $wp_customize ) {

	$text_domain = 'your_themes_text_domain';

	// layout
	$wp_customize->add_section( new JN_Customizer_Section_Title( $wp_customize, 'title_layout', array(
		'title'    		=> __( 'Layout', $text_domain),
		'priority'  	=> 1,
		'panel'    		=> '',
    'description' => '',
	) ) );
	// core settings
	$wp_customize->add_section( new JN_Customizer_Section_Title( $wp_customize, 'title_core', array(
		'title'    		=> 'Core settings',
		'priority'  	=> 90,
		'panel'    		=> '',
    'description' => '',
	) ) );
	// nav tip
	$wp_customize->add_section( new JN_Customizer_Section_Title( $wp_customize, 'title_menus', array(
		'title'    		=> 'Available Menus',
		'priority'  	=> 10,
		'panel'    		=> 'nav_menus',
    'description' => __('Tip: This can also work as a description in panels between sections.', $text_domain),
	) ) );
	// theme options
	$wp_customize->add_section( new JN_Customizer_Section_Title( $wp_customize, 'title_theme_options', array(
		'title'    		=> __( 'Theme Options', $text_domain),
		'priority'  	=> 120,
		'panel'    		=> '',
    'description' => '',
	) ) );

}