Sorry I can't help you with fireworks mx since I don't have that program (I have Paint Shop Pro 9).
To upload an image from your PC you need to have upload to an image site. I use photobucket.com (you have to sign up for it but it's free). I think you can upload up to 500 pics for free.
Here is the url:
http://photobucket.com/
Another image hosting site is ImageShack. I have heard about this site but never used it so I don't know how long pics keep on the site.
Here is the url:
http://www.imageshack.us