In order to add a date to a photo in Family Tree Builder:
1. Open your family tree in Family Tree Builder.
2. Click on the Photos button.
3. Double click on the photo to open the Edit Photo window.
4. Add the date.
5. Click OK.
6. Save your tree and sync it with your family site.
If you don’t use Family Tree Builder here’s how to add a date to your family site photos: How do I add a date to a photo on my family site?