You can reply to a message, including your own. Select the preview link at the bottom right, next to the post link. You will see a view like below. Find the "choose file" button, select the photo, click the Post button on lower right. Note that photos will not show up from the preview link. There are size restrictions, and a limit of 4 pictures per post. There is also a temporary modify link you can use to correct any problems. The modify only works for a little while, I do not know how much time you have to use it.
I hope to see some photos soon.