How do I create a set of images with thumbnails

I have a SaaS landing page into which I want to add some SaaS product screenshots using the lightbox element.

In addition to the lightbox element, I would like to display the thumbnails for the images just below the main image. Something like the image attached.

Any pointers on how I can do this?

Here is my site Read-Only: LINK
(how to share your site Read-Only link)