Wordpress Front end registration

functions.php

/***************************
     INSIDE FUNCTIONS.PHP
****************************/

/**
 * Formulario de registro
 */

//change register url for our custom one 
add_filter('register_url', function(){ return site_url('registrese');}); 

//Add extra fields to form
add_action('register_form','aulala_register_form');
function aulala_register_form (){
    $first_name = ( isset( $_POST['first_name'] ) ) ? $_POST['first_name']: '';
    $last_name  = ( isset( $_POST['last_name'] ) ) ? $_POST['last_name']: '';
    ?>
    <p>
        <label for="first_name"><?php _e('Nombre','mydomain') ?><br />
            <input type="text" name="first_name" id="first_name" class="input" value="<?php echo esc_attr(stripslashes($first_name)); ?>" size="25" /></label>
    </p>
    <p>
        <label for="first_name"><?php _e('Apellidos','mydomain') ?><br />
            <input type="text" name="last_name" id="first_name" class="input" value="<?php echo esc_attr(stripslashes($last_name)); ?>" size="25" /></label>
    </p>
    <?php
}

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

    if ( empty( $_POST['first_name'] ) )
        $errors->add( 'first_name_error', __('<strong>ERROR</strong>: Debes ingresar tu nombre.','mydomain') );
    
    if ( empty( $_POST['last_name'] ) )
        $errors->add( 'first_name_error', __('<strong>ERROR</strong>: Debes ingresar tus apellidos.','mydomain') );

    return $errors;
}

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

template-file.php

/***************************
     INSIDE FRONT END TEMPLATE
****************************/

<?php if( isset($_GET['register']) && $_GET['register'] == 'true' ):?>
										
	<h3><?php _e('Gracias por registrarte! Recibirás el password en tu email en unos minutos');?></h3>										
<?php else: ?>
	<form method="post" action="<?php echo site_url('wp-login.php?action=register', 'login_post') ?>" class="wp-user-form">
		<?php do_action('register_form'); ?>
		<p>
	        <label for="user_login"><?php _e('Nombre de Usuario','mydomain') ?><br />
	            <input type="text" name="user_login" id="user_login" class="input" value="<?php echo esc_attr(stripslashes($user_login)); ?>" size="25" /></label>
	    </p>

		<p>
	        <label for="user_email"><?php _e('Email','mydomain') ?><br />
	            <input type="text" name="user_email" id="user_email" class="input" value="<?php echo esc_attr(stripslashes($user_email)); ?>" size="25" /></label>
	    </p>
        
			<input type="submit" name="user-submit" value="<?php _e('Registrarse!'); ?>" class="user-submit" tabindex="103" />
			
			<input type="hidden" name="redirect_to" value="<?php echo isset($_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI']: ''; ?>?register=true" />
			<input type="hidden" name="user-cookie" value="1" />
		</div>
	</form>
<?php endif; ?>