How to add custom woocommerce-MyAccount-navigation on woocommerce account page

// Note the low hook priority, this should give to your other plugins the time to add their own items...
add_filter( 'woocommerce_account_menu_items', 'add_my_menu_items', 99, 1 );

function add_my_menu_items( $items ) {
    $my_items = array(
    //  endpoint   => label
        '2nd-item' => __( '2nd Item', 'my_plugin' ),
        '3rd-item' => __( '3rd Item', 'my_plugin' ),
    );

    $my_items = array_slice( $items, 0, 1, true ) +
        $my_items +
        array_slice( $items, 1, count( $items ), true );

    return $my_items;
}