First you go to https://www.google.com/business/ and sign in or register and follow the steps to create a local page.

The process works by allowing instant verification with Google My Business once you have a verified site on Google Webmaster Tools. You have to be signed into Google My Business with the same account you used to verify your site with Google Webmaster Tools.

There are three avenues to verification:

Postcard- Using the postcard screen you enter your address accurately and an optional contact name if necessary. Click "send postcard" When you receive your postcard you enter your verification code into your dashboard.

Phone- Click "verify by phone" and make sure you are able to be by your phone to receive the automated message. Enter the verification code into your dashboard.

Instant Verification- Use the process described at the beginning of this post. Some business categories may not be eligible.

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You have to signed in to Google My Business with the same account you used to verify your site with Webmaster Tools. And you use also one of other method of verification

http://support.google.com/business/answer/2911778