I have not tried it myself yet, but here is what I found on this sites help on forums.
Q. How do we add photos to our messages?
A. It is done the same way as on the old forums, and there are three options to adding a photo:
Upload a photo elsewhere on the Internet and type the URL at the bottom of the message you want to add in the 'Image URL' block.
You can use our variation of HMTL code in the body of the message to add a photo you have uploaded elsewhere. See the "Tools and Toys" link for instructions.
Upload a photo to the photo gallery and select it from a drop down menu of the photos you have in the gallery. This is the best option since a lot of sites will block you from using your photos elsewhere.
Here is the link"
http://www.pethobbyist.com/shared/forum_faq.html
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Mike
0.0.1 Green Iguana
0.0.1 Pac Man Frog
0.2.0 Albino African Clawed Frog
1.0.0 BIG Golden Retriever 105 lbs