If you using PrettyPhoto for your blog then you will see can insert property rel="prettyphoto"
now,you only insert anchor tag (a tag) is auto public lightbox.
This is tips
This code:
You change red line
Please test, You will see lightbox, .
for each image
This is tips
This code:
<link href='.../prettyPhoto.css' media='screen' rel='stylesheet' type='text/css'/>
<script src='.../jquery.min.js' type='text/javascript'/>
<script src='.../jquery.prettyPhoto.js' type='text/javascript'/>
<script type='text/javascript'>
jQuery("a[rel^='prettyPhoto']").prettyPhoto();
</script>
You change red line
jQuery(".post a img").parent().prettyPhoto();
Please test, You will see lightbox, .