How to View Social Actions by Source in Google Analytics

You can use Google Analytics if you want to see the number of actions such as Facebook likes, Google +1s and tweets that you're getting by source. For these steps to work, you must have current versions of the Facebook like button and Google + widgets running on your site. 

Steps

1. Open Google Analytics. Click "Social" under the "Visitors" tab. Then click "Action".
   

   Open Google Analytics.
2. Click Social Source below the graph.
   

   Click Social Source below the graph.
3. Click whichever social action you wish to graph and track directly. In the case of this example, the choices are Google Plus, Facebook, and Twitter. You will now see how people sharing content on your site is growing for each social network individually.
   

   Click whichever social action you wish to graph and track directly.

Warnings

• This will only work if your website has updated and connected code for the relevant buttons from Twitter, Facebook, and Google Plus.

Source : wikihow.com