Hello
I was wondering if there is a class that I can use to add a bar underneath my photos which contains the site url. I found some classes that add a watermark on the photo, however I want the bar to be under the photo.

Thanks in advance

I am not certain if you want the url to be a part of the image or just under it.
Of course placing a bar under the image is as simple as setting up a div or table and placing the div or cell beneath the image. Use some css and you can style it anyway you want.
As for making the url a part of the photo, I would say that you might need to actually edit the photos to have the url below them, then save them as the image you are displaying.