Ahhh, I found it. Okay, you use the [ img] tags, you can get them by clicking this button:

then put in the URL to your picture, in your example, like this: [img ]http://www.salviasource.org/images/gallery/1243.jpg[/img] except the space in [img ]http://should not be there, I just put it so it would show the tags instead of showing the actual picture. That would give you this:
