Load a external image

Im wanting to make a photo gallery that I can update easy, I thought if I could have a movieclip load external images for my thumbnails it would be nice but Im not sure how to set it up. I would make a file for my images and then another for my thumbnails, then if or when I want to switch out pictures I’d just have to drop new images into my folders and not even touch the FLA. Could anyone point me in the right direction with the right action script to use or a tutorial that explains how this is done…

And when I say load external I want it so I dont have to click on the image for it to load, I want it to just load automatically , I would put an invisible button or something to that efect over the images for a animated effect.

Thanks for your help.