I'm not sure if you have to be a member to upload pictures directly to the website or not. If you can do it, there should be an "upload attachment" form just below the form you use to make posts.
If not, but you have it or can post it somewhere else, you can attach to it using the Img button just below the subject line in the posting form. It puts something like this in your post:
If you can't upload an image and don't have a place to post it, PM me and I'll put it online and send you the URL.