Your picture needs to be updated to one of the various photo upload sites, e.g. Photobucket, Imageshack, Flickr. Once your picture has been uploaded, you need to copy the weblink, and paste it into your post, putting the following tags around the link [*img] [/img] (removing the asterisk).
Your picture will then show in your post. We reccomend Photobucket as it produces the tags for you!