Thumbnail links in Photo Gallery

This is my first post. Thank you for this wonderful site. I have used the Create a Photo Gallery tutorial (thanks to sbeener for the code). It works great, but would like to use thumbnails as buttons and link to a specific image. Have created the thumbnail buttons but am not sure how to target the specific image in the code. The code reads
on (release) {
_root.changePhoto(1); }

As you can see, I’m pretty clueless. Any help would be appreciated.