WP = add new customizer section(field)
IN CUSTOMIZER.PHP or FUNCTIONS.PHP
==================================
//register footer settings
$wp_customize->add_section('footer_setting', array(
'title' => __('Footer settings', ''),
'priority' => 25,
));
//Add settings for the phone number
$wp_customize->add_setting('phone_number', array(
'default' => __('Phone number', ''),
'transport' => 'refresh',
));
$wp_customize->add_control('phone_number', array(
'label' => __('Phone number settings', ''),
'section' => 'footer_setting',
'settings' => 'phone_number',
'type' => 'text',
));