Here is how to register your Free WordPress blog in Google Webmaster Tools:

1. Log in to https://www.google.com/webmasters/tools/ with your Google account.
2. Enter your blog URL and click Add Site.
3. In order to access most of the features, you will have to verify your site, so click on the Verify link.
4. You will be presented with several verification methods. Choose Upload an HTML file.
5. Copy the filename, which looks something like google1234567890abcdefgh.html
6. Leave the verification page open and go to your blog dashboard.
7. Create a new page (not a post) with the filename as a title and publish it. Don’t worry if the dot from the filename is stripped, like in google1234567890abcdefgh html.
8. Go back to the verification page and click Verify.

That’s it. Webmaster tool verification is done.