Gallery in portfolio post

Hello

I am trying to recreate, or nearly recreate, a gallery that functions like the one in the following link:

http://www.wearethenation.com/Interclick-Rebrand

Essentially, I need for the post to have text and a main image box. Bellow or above the image box a strip of thumbnails that when clicked will make the clicked upon image fill the main image box.

I am using the Classica Theme and will be trying to apply a gallery to this website:

http://wp.wearethenation.com

Any help would be greatly appreciated.

Thank you