New to this forum and want to see if I can get some help.

I am building a photo portfolio site. Using Dreamweaver. I have two different tables.
The first one has thumbnail images.
The second is where I need help.
It is a 400x400 square table - I want the larger image of the thumbnail to appear in this table when the thumbnail is clicked.
Does anyone know how to do this???

Thanks in advance for any help.