Start a new post and write your subject and a description in the body, then look down and hit BROWSE by the file attachment box. Select your photo and hit POST. Do not preview. It seems to not "take" the attachment with a preview many times. Also, maximum attachment size is 60KB.
If for some reason it's not how you like it after you POST it, you can always edit it.
If for some reason that doesn't work for you, and you're somewhat savvy, you can upload your photo to an online server like photobucket or your own isp and then create a link to it. Or, you can also use the PHOTOS tab above and put it in the actual photo album.
-Dawn-