Adding a download link to photoblog

Hi all,

I have a photoblog. The theme I used has an overlay over the full size image so you can click next or previous (lightbox style). Because of the overlay, viewers can’t right click and download the image if they want to.

What do I need to add to put a link under the image that will allow the user to download the image it’s displaying.

Here’s the code used to display the image:

<div id="topcontent" style="width:600px;">
	<?php if (is_single()): ?>
	<div id="theoverlay_holder" class="overlay" style="left:0;top:0;z-index:100">
		<div id="theoverlay_panel"></div>
	</div>
	<?php endif; ?>

	<div id="overlaynav">
		<a><?php echo $prev_post_perm?>"<?php else:?>" style="display:none"<?php endif;?> id="overPrevLink"></a>
		<a><?php echo $next_post_perm?>"<?php else:?>" style="display:none"<?php endif;?> id="overNextLink"></a>
	</div>
	<img id="mainimage" src="<?php echo get_thumbnail();?>" alt="image" />
</div>