Wordpress insert post PHP

WP insert post PHP function and Custom Fields

$my_post = array(
    'post_title' => $_SESSION['booking-form-title'],
    'post_date' => $_SESSION['cal_startdate'],
    'post_content' => 'This is my post.',
    'post_status' => 'publish',
    'post_type' => 'booking',
);
$the_post_id = wp_insert_post( $my_post );


__update_post_meta( $the_post_id, 'my-custom-field', 'my_custom_field_value' );