Follow the instructions on this page: https://support.google.com/webmasters/answer/1408986?hl=en
For me, I chose option 2 which meant:
- Adding a picture to my Google Plus profile
- Adding a contributor link to my site from my Google Plus profile
- Modifying the footer.php of my theme to include the author link.
I changed the link slightly from the example to have my name as the link text.
<a href="[profile_url]?rel=author">John M. Solberg</a>
If you look at the bottom of the page, I’ve added a copyright line. My name is that link to my google profile with the rel=author parameter.
Google has another tool for testing. Go to this page: http://www.google.com/webmasters/tools/richsnippets and enter your site URL. It will show you if your Authorship setup is working.