Click the "Attachments" icon, which will bring you to the bottom of your "compose" screen. Click "Choose File" and select the file that you want attached. The name of the file should now appear in the Attachment box. Click the "Attach" button. The file name and the size of the file should appear in the Attachment box. Please note that the process of uploading and attaching a file may take a few moments for larger files and/or slower internet connections. Please be patient and do not click on other things while you are waiting.