Hey, I had to ask to. It has been quite some time since I posted a pic but first you have to put it on one of those pic sharing sites, Flickr, Shaw etc.
then take the url code that the pic is given on the site and insert it into the "insert image" box (that is the box on top of the post reply box that looks like a mountain peak and a postage stamp) and then you're basically done. Somebody is sure to correct me if that is wrong.
Imageshack is a quick way to host pix.