I'm trying to create an effect that makes it so when someone runs their cursor over the gallery name the thumbnail appears next to the gallery name. I know how to do this with java in html but not sure how to apply the effect to a php page, does anyone have any suggestions how to do this?

This would be in any case not Java but Javascript. That is a huge difference... I recommend to read the theming tutorial to learn how Zenphoto themes work (and that it is actually html).