How to add author information in Google search results

How to enable the author information in Google search results as shown for many posts?

As a post writer, we may want our authorship information to appear in search results. To do this, we need a Google+ Profile with a good, recognizable headshot as the profile photo. Then, verify authorship of our content by associating it with your profile using the methods provides by Google:

Author information in search results: http://support.google.com/webmasters/bin/answer.py?hl=en&answer=1408986

Structured Data Testing Tool: http://www.google.com/webmasters/tools/richsnippets

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The easiest method (also used on https://www.systutorials.com ) may be linking your content to your Google+ profile. If the site uses WordPress and the “Biographical Info” is used (like Fclose.com), the authors can add the link to the Google+ profile in their biographical info field in their profile.

Create a link to your Google+ profile from your webpage, like this: <a href="[profile_url]?rel=author">Google</a> Replace [profile_url] with the your Google+ profile URL, like this: <a href="https://plus.google.com/109412257237874861202? rel=author">Google</a> Your link must contain the ?rel=author parameter. If it’s missing, Google won’t be able to associate your content with your Google+ profile.

Add a reciprocal link back from your profile to the site(s) you just updated. Edit the Contributor To section. In the dialog that appears, click Add custom link, and then enter the website URL. If you want, click the drop-down list to specify who can see the link. Click Save. To see what author data Google can extract from your page, use the structured data testing tool.

— https://support.google.com/webmasters/answer/1408986?hl=en