Some notes I took which may help:
On the app I can click on the photo album icon or just copy a link in from a website like photobucket.
To post photos as a displayed image -->
A): Upload a photo to your AA album.
On desktop AA website OR mobile AA full website version. Go to User CP (top left) --> go to Pictures & Albums (left side) & add album / upload photo.
Select BB code from AA album (below your selected photo displayed) and paste to your AA post. E.g.
[IM G]http://www.aquariumadvice.com/forums/members/10352-albums14473-picture69767.jpg[/IMG]
B): Or select photo link as an image (IMG) from your photo hosting site and paste to your AA post. E.g.
[IM G]http://img.photobucket.com/albums/v311/220gtiturbo/2015-11-03%2018.15.38_zpsljtxaqrp.jpg[/IMG]