If you want to post a picture in the "images, art, and poetry" forum for instance you first need to establish a free geocities, photobucket, or other such account on the web to which you can upload your picture or art. Once that upload is accomplished you can enter the web address for your picture or art in the "URL" dialog on the MS image posting page and like magic, your picture will show up where you want it posted.
"Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting 'Holy Shit! What a ride!'" ~Hunter S. Thompson