Right click on the photo you want to attach.
Chose Properties and Highlight all of the info in "address" and copy.
Click "Image" from the post area to add BBCode
Paste the Address info into that pop-up box.
Hit submit and a photo will appear with your message.
Here's the address for the attached picture for example:
http://image60.webshots.com/160/8/69...6fzfxBY_ph.jpg
And using the BBCode box:
The BBCode box basically just adds [IMG] on either end to display the photo.