Your webinar is automatically launched in Listen Only mode. You may change to Q&A mode in the Webinar Options menu:
This allows attendees to un mute themselves. An Announcement will be heard letting them know when you switch to this mode.
To silence the webinar again, just set it back to Listen Only mode.
Audio Options are available on the screen as well so you may check your microphone and speakers or switch to phone.
Invite Others will allow you to quickly invite more people or pass out the link to your webinar.