Actionscript beginnger, PNG gallery transition, filez included

Hello everyone, and thanks in advance. I am relatively new to actionscripting for about three months. here is my problem

I am using loadclip, to load a PNG into an empty movie clip, but when I click on my thumbnail buttons my content abruptly appears unto the screen.

I would like to create a transition that fades the alpha of a new image from 0 - 100 on top of underlying image.

below are the files, and ive included the first four pngs from the portfolio section.

www.atelierfrancois.com/index13/Gallerytransition.zip