I have problem with jquery free gallery. Some thumbnails don't display images completely.

Q: When I choose the photos for the gallery, how can I get them to center correctly in the thumbnail view. Some of the pics are not centered. Do I have to resize the pics?

A: Unfortunately, it's impossible to control aspect ratio of thumbnails. But you can you can use your own images as the thumbnails for visualLightBox gallery.
You should manually correct the code for BODY section of VisualLightBox in that case, for example:

<!-- Start VisualLightBox.com BODY section -->
<div id="vlightbox">
<a class="vlightbox" href="data/images/9.jpg" title="9"><img src="images/YourImageName.png" alt="9"/></a>
<a class="vlightbox" href="data/images/7.jpg" title="7"><img src="data/thumbnails/7.jpg" alt="7"/></a>
<a id="vlb" href="http://visuallightbox.com">Photo Gallery Creator by VisualLightBox.com v5.0</a>
<script src="engine/js/visuallightbox.js" type="text/javascript"></script>
<!-- End VisualLightBox.com BODY section -->