Or you can write a one-line HTML code and include it right here in a post like Michael did, above. I
think there is a hint for that in the Tips section here, too. You still have to post it to an image-hosting site first though (like Photobucket.com), I'm pretty sure, to get that "_" part of the code.
Then there is nothing typed into the "image URL" box here, just the picture in the message. Especially useful if you have a lot of pictures you want to include in your post, like Cheezz did with the cookies she made (yum!).