The first step will be accessing https://www.google.com/webmasters (make sure you are logged into your Google Account).
After accessing the link above, just click at the "Add a Property" button and type in your domain's name:
On the next screen you'll be asked to verify your domain's ownership with Google.
Click on Alternate Methods and select HTML Tag. This tag will be pasted into your site manager to verify the ownership of the domain.
After you get the HTML Tag, just go to your site manager.
Access Configuration -> Google Integration and hit "Google Search Console"
Just paste the metatag provided by Google and hit Save.
After this, just go back to your webmaster's page and click "Verify".
And there you go! Your domain is now verified by Google!