Thread:MP999/@comment-34964696-20170315043746/@comment-27190018-20170326051359

All right, I've taken a look.

At the bottom of the image grid, there's an option that says "add a photo to this gallery". Click on that. That will bring up an editing window with your gallery in it.

Hover your mouse over one of the pictures, and a prompt that says modify/delete should come up. Click modify.

This brings up the option to add a caption to the image.