How to Post to Your Company Domain in Google+

By Jesse Stay from Google+ Marketing For Dummies

If you use Google Apps for your business, you may want to post updates that coworkers only can read. This can be helpful to your employees To post such an update, follow these steps:

Write your message.
Click Add Names, Circles, or E-mail Addresses in the circles box.

Or click Add More to add to the existing circles.
Select your company’s domain from the drop-down menu.
Publish.

You’re all set! Your update will appear only to employees of your company.

Keep in mind that if you specify any other circles with your company domain, the update will also be visible to those circles — so be careful of who can see your update.

Turning on social ads does a couple of things:

It links your ad’s +1s to a URL or a Google+ page. When people +1 your ad, their friends see (in the Google search results) that they clicked the ad. Those results also get a higher ranking due to the increased number of +1s.
It allows people to see the friends who have liked the ad, increasing click-through and conversion due to social pressure. Below the ad, people see pictures of friends who +1’d that URL or the ad itself. When they see that picture, it makes them want to click the ad as well.

Google offers even more information about integrating social ads.