pop up window with links

Hi,
I'm having an issue here.
I'm using DW to make some codes for me.
I have thumbnails on my page I want to open in a new window for each photo.
I have the code and it works. Click on the thumb, a window pops up the size,
etc. that I want.
That's all great. But........
Question:
My pop up window will have arrows on it so you can continue to see other
photos all associated with that thumbnail.
How do I go about making the arrow in the pop up window when clicked on have
another picture show up in the same window?
Is there a specific behavior needed to do this?

I've tried several different ways, but nothing is working.
Thank you.
Lori

http://ebycustompainting.homestead.com/MOTOR1A.html

Here is an example of the window. (it's not to correct pop up size here, but
just to show you)
I want to be able to click the arrow while in the pop up widow, and the second
photo shows up. Then click on the back arrow to go back to the first photo.

Thank you for any advice.