If you're looking for guidance on how to implement a gallery, this example may help:
<div class="gallery">
<div id="mainViewport" class="viewport">
<img src="my-picture.jpg" alt=""/>
</div>
<ul class="thumbnails">
<li><img src="imgs/my-picture-thumbnail.jpg" alt=""/></li>
<li><img src="imgs/my-picture2-thumbnail.jpg" alt=""/></li>
<li><img src="imgs/my-picture3-thumbnail.jpg" alt=""/></li>
</ul>
</div>
<script>
var mainViewport = $('#mainViewport');
$('.thumbnails img').click(function(){
var path = $(this).attr('src').replace('-thumbnail','');
var mainImg = new Image();
mainImg.src = path;
mainViewport.html(mainImg);
});
</script>
To make this work, ensure your thumbnails are named as 'path/to/full/img-thumbnail.jpg' and strip the '-thumbnail' part in the script to display the full-size image in the mainViewport div.
For a live demo, check out: http://jsfiddle.net/wbT4N/1/
Remember to have both thumbnail and full-sized versions of your images for this to work properly.
Best of luck!