what do I need for a webinar
http://www.blog.getsocial101.com/usinggooglehangoutforwebinar
You can broadcast your Hangout publicly. You can record it, edit the output, and share the recorded event online.

There are tons of ways for small businesses to utilize hangouts to connect with their clients, construct their brands, increase profits for their businesses, and create buzz.

Perhaps you have a newsworthy announcement – a new executive, a new product, or to announce that you’ve won an award, hangouts let you tell the whole world and keep an interactive record of the announcement.
Using Google hangout for webinar

Public relations Taylor Swift held a hangout to announce her latest album. As soon as her single was released it went directly to the top spot, faster than any other song in history.

http://www.blog.getsocial101.com/usinggooglehangoutforwebinar

related google hangouts videos
http://youtu.be/Z2f4O9rWci4