As a webinar viewer, you get an invitation from the webinar speaker.
After you have clicked on your webinar invitation, you see the following.
In this case, it is one single person who hosts the webinar. As an example, if a second person would also speak to the audience, another person would be displayed in the video. Up to 9 people can be visible in one webinar stream.
As you can see on the image, you have the possibility of making comments or asking questions during the webinar. You only have to write a message and click on Send.
Only the webinar speakers see your messages. They can decide if they want to display these questions in the stream or not.
So simple ;)