1. Log into your Shopify account, and click on "Online Store"
2. Click on 'Themes' on the left, and then on 'Customize Theme' on the top right
3. Click on 'Themes Options' and then on 'Edit HTML/CSS'
4. Search for: </head>
5. Paste the Google Verification Code one line above the </head>
6. Click 'Save'