You will need to upload your photo to a hosting web service that is on the Internet such as your web server or a hosting photo service such as
http://photobucket.com/ . You can not link from your local computer's hard drive.
The first is a Direct Link that you would have to high light with the mouse and then click the Img button in the reply message.
The second picture uses the built in link that Photobucket and maybe other site supply. Either way, you will want the link embedded between the commands.
Generally, one would resize the picture so that it does not take such a large area as my pictures.
Image before and /image after the link
Yeast:
makes
