Add Registration field Woocommerce

functions.php

<?php

//1. Add a new form element...
add_action('register_form','myplugin_register_form');
function myplugin_register_form (){
    $first_name = ( isset( $_POST['first_name'] ) ) ? $_POST['first_name']: '';
    ?>
    <p>
        <label for="first_name"><?php _e('First Name','mydomain') ?><br />
            <input type="text" name="first_name" id="first_name" class="input" value="<?php echo esc_attr(stripslashes($first_name)); ?>" size="25" /></label>
    </p>
    <?php
}

//2. Add validation. In this case, we make sure first_name is required.
add_filter('registration_errors', 'myplugin_registration_errors', 10, 3);
function myplugin_registration_errors ($errors, $sanitized_user_login, $user_email) {

    if ( empty( $_POST['first_name'] ) )
        $errors->add( 'first_name_error', __('<strong>ERROR</strong>: You must include a first name.','mydomain') );

    return $errors;
}

//3. Finally, save our extra registration user meta.
add_action('user_register', 'myplugin_user_register');
function myplugin_user_register ($user_id) {
    if ( isset( $_POST['first_name'] ) )
        update_user_meta($user_id, 'first_name', $_POST['first_name']);
}