Upload the photo to a website like https://imgur.com . Then follow the instructions from the F.A.Q. (Included Below)

"Adding Images
To add a graphic within your message, just encase the full URL of the graphic image as shown in the following example [the asterisks must be removed for it to work].

[*img]http://yourdomain.com/images/picture.gif[/*img]

In the example above, the BBCode automatically makes the graphic visible in your message. Note: the "http://" part of the URL is REQUIRED for the [img] code."