Portfolio scaling frame

I am wondering if someone could help me in giving me a direction or solution to go about my portfolio

www.jamespg.com/new.html

I want the buttons the left to load up the images in the main frame but before doing that have the frame tween to the proper size to fit that image.

can I give my button direction into knowing what size to tween to before loading the image up?

I need some help please.
Thanks