You have to host the image somewhere else first. We do not have allocated space for hosting our customer's images mainly because there was never a big interest. There are alot of places you can host images for free. http://photobucket.com
to name one is a good example of this, and one I would recommend.
After that, when you make your next post and want to include a picture, click the Img button first, then type the url where the picture is located (aka http://www.someplace.com/picture.jpg
) and then click the Img button again to close the "tags" for the image.