To get a photo up, you need to click on the "Reply" button under a post. Don't use the "Quick Reply" box at the bottom of the page.
Then below the reply area, you will see "Attachments and other roptions". Once clicked, you will see "Choose file". Do that, and the pics will appear in your post.
There's a limit to the size you can post. I find choosing 512 pixels wide is usually OK. And you can only post three pics per reply, so, if you have more pictures, you will need to make another post or two.