Administrators can start live class sessions using the Start live class session (red rectangle area) action as shown below.

When user click on the live class session option, popup dialog will appear which asks to select the video conferencing service type. You can go with built-in service or an external service.
If user proceed with built-in service, it will redirect you to basic instructions page.
Admin can start live class by clicking on Start Live Classbutton at the bottom of the page. It will initiate a live class session in the system like below.