Code Needed: Generate a pop-up window from a flash photo gallery

Hi! I know the basics for flash, but really not familiar with Action Scripting. I have a gallery that I purchased from iStock; it has thumbnails and a main image chosen from the thumbnail. It has an xml doc where I can change/add or delet images. I want to be able to click on whatever main image that has currently been selected and have a pop-up window appear with additional photos on the item selected.
I know that the action code needs to be done in the main gallery - just not sure of what that code would be. I also know that I will need an xml doc that will call out the variables; again not that familiar with xml.
Can anyone help? Please?