Dennis,
Start a reply. Make sure "Rich Text Editor" is selected above the top of the text box. Click on the "Image" icon in the 2nd line of icons, just right of center. It looks like two small mountains with the sun rising above them. When the "Image Properties" box appears, click on the "Upload" tab along the top. Click "Choose your file", and select the file from your computer that you want to send. Click "Send it to Server", click OK, and it'll upload to your message. Attached is the "Image" icon.