Not sure, I'll investigate and get back to you.....
EDIT
I dont think that you can. The best solution I have is to put the picture on photobucket and then using the code button (hash key, third from right above) put a direct link to the picture between them. It should look like this.
"[ code ] photobucket link [ code / ]" (I've put spaces to stop it working)
And when done right you should get this in your post.
http://i138.photobucket.com/albums/q252/kaptainjimmyladd/Alfa20Romeo1.jpg
Regards,
Jim Gough
Looking for a Mk6 Rapier....