Write your message, attach the images as attachments, hit the post button
When the page reloads, scroll down to your message and click on each thumbnail (if multiple) to expand it. Right click on each image, select Copy Image Location (in firefox) and paste it in Notepad or something or just leave it in Clipboard if it's only one image.
Then hit the modify button and use img tags with the url between them
unrelated image attached
