<?php
$name_section = 'bws_new_section_custom_css';
$wp_customize->add_section($name_section, array(
    'title' => __('Custom css', 'aible'),
    'description' => 'You can add css in here',
    'priority' => 101,
));

$arr_field = array(
    'bws_custom_css' => array(
        'default' => '/*** Custom ***/',
        'name_control' => 'Customize_Textarea_Control',
        'label' => ''
    ),
);

$BwsCustomize = new BwsCustomize();
foreach ($arr_field as $field_name => $val) {
    $BwsCustomize->create_filed_customize($wp_customize, $field_name, $val['default'], $val['name_control'], $val['label'], $name_section);
}