To embed pictures in messages, find the picture you want in your album (or anywhere on the web), click on it to bring it up to full size if needed, then right click on the pic and choose whatever your browser uses to copy the image address (in Chrome it is Copy image address which is real simple; others can chime in with the command used by other browsers). Then when typing your message, paste the URL that was just copied, highlight it in the message box, and click the Img tag at the top. That will put the tags at either end of the link. You can click Preview to ensure that it works.
The most frequent mistake people make is copying the URL for one of their pics from the address bar. That link is too long, and rarely works with the Img function. Copying the image address gets you a more concise URL. To see what I mean, right click someone's embedded photo, copy the image address and paste the URL into the address bar and click Go. All you will see is the photo on an all white page.
Clear as can be, right? But you only have to make it work one time to see how easy it really is.
Good luck!