Actionscript 3.0 :: Load Images To A Holder?

i am looking to have a number a small thumbnail pictures on a page, and with either a roll over of the mouse or a click i would like them to larger on the screen.

i am guessing i need to have a holder to load them in but i dont know the script i need to load a picture from the library this what i have so far but i just dont know the code to load images to a holder

function image_click (mye:MouseEvent):void{
}
image_btn.addEventListener(MouseEvent.CLICK,image_click);