How to get a text lightbox when you click on an image (e.g. for a bio)?

Hi, I'm new to the site and to coding, so please forgive the ignorant question! I've found some really helpful code to let me create a text lightbox when you click on an image (e.g. for a bio on a team page). However, at the moment my image box is empty as I'm not sure what to put in the code to link it to a photo of a team member. How do I identify what image I want to have on my team page (which will then be the click through to the lightbox)?

Hope this makes sense, and thanks in advance!

Hi heathelise

Please send us the site url so we can identity your issue