The Google Author Tag allows your blog and articles to link back to your author page giving you better credibility, and lets people know who you are by showing your Author page in the search results which will drive a better click through rate and gives better credibility.
The first step in adding the Google Authorship Tag is adding it to your site.
  If you have a blog, like I have here the first thing to do is add this tag to your author page or blog:
<a “url fn author” rel=“me” href=https://plus.google.com/112480022787124899502/about >
*Note Make sure you have a headshot of yourself.
This will connect to your Google+ About Page as seen below. Follow next step below screen shots.

The next step is you want to edit your contributor to section as shown above and put in the URL of your blog or About page on your site.
Head on over to Google's Rich Snippet page to verify the tag is working. Type in your blog, post or article and check the results to see if it is verified.
 
 There is another way to easily add your Authorship is to have a verifiable e-mail address of the domain that your blog and articles are on and head on over to the Google Authorship page on Google+ and submit your e-mail address and verify it.

The last step you need to do is add a Byline like I have below and make sure your name shows exactly like it appears on your Google+ Profile.
Add this Byline to your blog or About page.
By "Shawn Lippert"