Append an attachment to current lesson

1) You need to upload attachments to server before appending them to a lesson.
(from the main menu, select Options, and then click on Upload files. See Upload Files under Options submenu )
2) you must have this screen visible on your monitor
3) Click on Attach Files button attachment_button
4) If you see this screen, then you have not uploaded your files to the server.
Upload first
Click on Options submenu and upload files (attchments)