Thank you for your fast response.
I am not really good at php so I did not fully understand you documentation.
What I have found working was:
<?php
$args = array(
'post_type' => 'attachment',
'post_mime_type' => 'image',
'post_parent' => $post->ID
);
$images = get_posts( $args );
foreach($images as $image): ?>
<a rel="lightbox" href="<?php echo wp_get_attachment_url($image->ID); ?>" title="<?php echo wp_specialchars( get_the_title($image->ID), 1 ) ?>"><?php echo wp_get_attachment_image($image->ID, 'medium' ); ?></a>
<?php endforeach;
?>
I found out that with this plugin, it just adds images as attachments. So I found this code to just show all the attachments.
I love your plugin, and it works fine now. Thank you very much.
Maybe you could update the documentation for the people that also had the same problem as me and do not know what to do.
Keep up the great work ??