Go to Webinar > Upcoming from the left navigation bar in your RingCentral app.
Click the Start button beside your scheduled webinar.
Clicking start will launch the webinar as a prep session with your co-hosts and panelists can join. Attendees will be waiting in the lobby. Click Go Live on the bottom right corner when you are ready to start the webinar for your attendees. Once you go live, the attendees will then join the webinar.