Open thumbnails in lightbox

I am running a customized version of Graph Paper Press’s fullscreen.

Rather than clicking a thumbnail and being redirected to a new page, which is tiresome, how and what can I use such that clicking the thumbnail will open either the image in a lightbox/fancybox/etc or open the post itself in a box?

I think I can use facebox to achieve that but I’m not sure where the a href links are generated for the thumbnails (not familiar with PHP).

A little help please? : )

My URL is here.

Here’s an excerpt of how the thumbs are generated (I believe). I think this is staring at me in the face but I need to teach myself PHP. Hopefully this can be easily answered!

<div class="home-thumbs">
<?php $home_query = new WP_Query("cat=&showposts=6"); $i = 0; ?>
<ul class="thumbs">
	<?php while ($home_query->have_posts()) : $home_query->the_post();
	    $do_not_duplicate = $post->ID; $i++; ?>

	    <li class="post-<?php the_ID(); ?> thumb-big"><?php get_the_image( array( 'custom_key' => array( 'thumbnail' ), 'default_size' => '320x320', 'width' => '320', 'height' => '320' ) ); ?></li>

    <?php endwhile; wp_reset_query(); $i = 0; ?>
</ul>
</div>