[Theme: WP-Creativix] Featured Image as Lightbox link?

I would like the “featured image” that is shown in the slideshow of the main page to be a link. Either to the same place the “read more” link goes, or preferably a gallery view of the full image. What I mean by gallery view is on individual pages in a portfolio (by clicking “read more”) under the post it has “Gallery” and if you click on one of those the image pops up in a sort of lightbox (rest of the page dims, just image centers on screen with a X top right corner or you click off image to close).
Very basic PHP and fairly basic CSS knowledge. Thanks for any help.