Jerry, you will have to upload them to a picture hosting site first... either to your own webpage or to a place like Shutterfly or Webshots.
After you have them uploaded, view the picture, right click on it and click on Properties.
In the Properties box, copy the Address (URL) it should be near the bottom... When posting click on the Insert Image Icon about the message box and paste the URL into the box that opens, this will put the web address between [IMG] tabs