When we add a new website to any of the webmasters tool we need to prove its ownership, and that can be done in a couple of ways like uploading a page to your server or adding a meta tag to your site header.
Uploading a file to server to verify ownership
Webmasters provide a file that we need to upload to our domain root folder, if we are successful in doing so webmasters verify site’s ownership. This is a better way if you are using a cms like wordpress or drupal, because even if you change your theme, you are still a verified owner of site. We recommend usage of meta tag to verify ownership only if you are unable to access root directory.
Adding a meta tag to head section to verify domain ownership
Just check out head section of your webpage and add the code provided by webmasters
code would be something like this
If you are using wordpress click on appearance – > editer – > click header.php and find < head> tag and add the code just below the opening header tag.