When replying or making up your message put picture address into the 'picture maker' by clicking on the yellow box icon with the mountains, this will bring up a small window, paste address in there. If you place cursor over yellow Icon it will tell you it is the "insert Image facility.
I think by the look of it you posted image code straight into the message, they can be seen by double clicking on them.
Now a question for you, how long did it take to upload pix to steam scenes site?
Cheers Rog