I can't find anything in the instructions that tells you how to post a photo
In order to post a photo, it has to "live" somewhere on the web (ie. not just be on your computer). What internet photo hosting site do you use? I use photobucket but I assume other photo sites are similar. Once your photos are on the web at a host site, you can start a message on this site, then open your photo site and copy the photo you want, then move back to this site and press paste. So it is just a copy-and-paste function once you have your photos uploaded. Hope this helps.
A few of the forums on Garden Web do allow one to post a photo. The "Kitchen Table" does not. As explained by the poster above, this forum provides a place to store a link to an image file that resides somewhere else on the internet.
But that is not all bad. The forums in Garden Web that permit images limits the file size to 60 K bytes. That is barely enough to display low level photos, enough for you to get an impression of what the picture is about, but not enough to show a high quality picture of any size. That limitation disappears for linking to an external site where an image is stored. Any limitation therein is set by the arrangement between you and the external site such as "Photobucket".
Ooops! In my prior post, I mentioned "Kitchen Table" when it should have been "Antiques and Collectibles". However, both of these operate the same way for posting an image.