How to have a lightbox of different content (written) pop up when you click an image

Hey Everyone, 

Looking for some help on adding a lightbox with unique content to pop up when an image is clicked to display a person's bio.

I've tried using this person's code - 

However I found that it would only add the button to the top of the page in the header and it's not moveable.

Can anyone help or advise how they've done something similar? Template being used is Sackett.

Thanks a lot!! Really appreciate any ideas