Regardless of how you setup your Google Hangout ( see this document) this tutorial will walk you through the process of inviting guest and running the Hangouts.
The first thing you will want to do is invite people to join your Hangouts. On the initial screen you will see a box where you can invite individuals:
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They receive an email containing the join Hangouts link:
For the individual to join the Hangout they simply click the “Join Hangouts” button
This is the main Hangouts Screen:
The bar in the upper right hand corner allows you to invite additional people 
, select your camera, mic, and speakers , and access a few additional tools 
We talked about adding people to your Hangouts above.
The gear icon 
allows you to select your camera, mic, and speakers.
The three dots give you access to a few additional Hangouts tools and helps.
As you see you can access the chat feature from here or you can click on the chat icon 
in the lower left corner of the screen.
From here you can send a chat to the entire group in the Hangout. You can also show or hide the chat window from here.
The three icons at the bottom center of your screen are to mute your mic or camera and to hang up the call.
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