If you have Supporter status (see
here), you can now attach a file to a post in selected forums (currently only in the "Pictures and Movies" forum), such as an image. Remember that only some file types are allowed, such as GIF and JPEG images, ZIP files and some others.
Also don't forget that each post has a limit of 64 Kb for the attachement.
Just use the control:
at the bottom of the post editor to select the file to upload and post as usual.
Mario Sobral