Once the organizer or participants join the webinar, the service will check the preinstalled pieces of equipment and show a warning if your computer doesn't have any webcam or microphone connected. 

After you join the webinar, you will see the window where you can set up the webcam and microphone. Choose the webcam and mic, adjust the microphone volume.

To reopen the Settings window, click Settings in the top right-hand menu. 

To run a webinar, switch on the webcam and microphone. To do this, click the corresponding icons on the upper panel.