Customize Product Info Page

[techiegirl]

I am needing to customize my product info pages similar to the layout of the attached image.

Specifically changing the "Add this to my Cart" button and changing the "Tell a friend about us" button to a basic link that appears right below the image.

Can anyone point me to the specific php pages and styles that I need to use to modify the layout?

Link to my site is http://www.tregreekboutique.com/zencart

Thanks!