I was having the same problem. What fooled me was the photo icon up above where you would write your post (this section). You don't actually click on that but below this section on the left you will see attachments and other options. That's what you need to click on.
I don't know what I'm doing!
Got a couple pics to post, but it tells me max size is 300kb, don't know how to reduce size on an IPad, and why did 2 pics post.
Sorry to be such a stoop, but I obviously need lots of help!