Pilliau all you do is copy the link from your online pic's...when you come to reply to post a new box comes up...then look up a yellow box with a small triangle top left of the box...click it...img img comes up then right click between the img img click preview then close box if you are happy & post once you have done it once there will be no stopping you [8D]
have right-clicked over your facebook pic to 'copy image location' then right clicked again to paste it in between (img) tags looks a little like this...