intergrating a slideshow into page.php

I am wanting to create a slideshow that is not in the content section of my page but in another area. I would also like to be able to use the image uploader to uplaod image to the pages and the from the page.php call those images and display a thumbnail and a large image using this script: https://spaceforaname.com/gallery-light.html

What I don’t understand it how can I grab the images and have them so when the thumbnail is clicked the large image changes?