Photo gallery implementation

Hello, back with AM2 I used to had some photo galleries on my articles.

Now, I'm trying to convert my old photo galleries on each article to my new CMSBuilder.

I'm using this code, and the thumbnail image its not showing, while my regular pic with the pretty photo effect shows properly.

<strong>Fotograf&iacute;as:</strong><br/>

<?php foreach ($accesandoRecord['images'] as $upload): ?>
<ul class="thumbs">
<?php if ($upload['hasThumbnail']): ?>

<li><a href="<?php echo $upload['urlPath'] ?>" data-rel="prettyPhoto"><img src="http://www.mundoregio.com/php_helpers/timthumb.php?<?php echo $upload['urlPath'] ?>"></a></li>

<?php endif ?>
</ul>
<?php endforeach ?>

Am I doing this implementation properly?, I mean, Am I on the right way?

I need to figure it out how will my thumbnail image will show here or if there's an in-house tool inside CMS Builder to display thumbnails and then give the prettyphoto effect on each pic.

Thanks.