To post images, first upload them to a website and then link them using stardard HTML. If only one image is required you can put its URL in the "Optional Image URL" field. Otherwise, use "img src" tags.As for copyright, that's determined by federal law. The person making a post always retains full rights to any post they write on a public messageboard or anywhere else, for that matter. By posting, you imply license to display and archive the post, but you retain full rights to it.
In most cases, it's a non-issue because posts are usually pretty trivial. But if you post something significant, it might matter to you who owns the content of your post. In either case, don't worry. Federal law is not ambiguous about copyright ownership. You own what you write.