WPAssociate plugin

I recently installed the WPAssociate plugin on my site. I have selected the option to have products appear in rows of three, but instead they appear as a single column down the middle of the page. How can i fix this? I only installed the plugin, not the included theme.zip. Does this plugin have to be used with the included theme or can it be used with any theme? Is there a page template i can use? Any help is appreciated! The page link is: http://www.hitechdigitallifestyle.com/desktop-computers/