How do I add photos to a message?
If you're replying to a post, there is a button labelled "Add Photos" directly above the "Send Message" button that you can click to add photos to your message.
If you're replying to a message on the messages page, there is a button labelled "Add Photos" that is directly below the message text area that you can click to add photos to your message.
If you're replying to a message by email, you can simply attach photos to your email to send them to the other person (just make sure to attach the photos individually and not as a zip file).
If none of the above work, you can upload your photos to a site like Flickr, Dropbox or Google Photos and then just include a link to those photos in your message.