Thank you for your business and also for sending over the link. I took a look at your site and it appears that you did add the images correctly. You are also right that some of the plugins are causing the trouble.
Here’s a quick rundown of what I found:
The Next Gen Gallery plugin is loading loading a slideshow script that’s also used by the theme.
The Easy Fancybox plugin is also duplicating a script that’s included in the theme. If you’d like to use the plugin, then you’ll want to select “no” in the theme options page where it asks to use the lightbox gallery.
You could try disabling those plugins and see if it works then. I played around with the source code on your site and was able to get the slideshow moving that way.