Adding Text to Images in Lightbox Only (Zion)

Site URL: https://www.charlieriback.com/

Hi all!
I'm running a portfolio website using the Zion template. I'm wondering if there's any way to have text and descriptions for images show up only in lightbox, when you click on them. Right now when I try to add text to an image it appears right below the thumbnail of an image only, using up a lot of space on the actual page. 
If the solution has to do with lines of code, please let me know if there's anything I have to do other than paste it into the CSS section (I'm pretty poorly versed when it comes to coding).

Thanks!

Hi,

Try code in this question