In your account select Projects and Activities > My projects.
When the ownership of a project has not been confirmed, the following message appears by the selected project: “Website ownership is not verified! Please add the code to the site header <head></head> area and press the “Check” button."
The verification code must be uploaded on the website only for a short time for us to verify that you are the real owner of the website. To place the above code, you have to be able to edit the homepage of the website and place the meta parameter in the header parameters of the website. Once the verification and confirmation are done, you can remove the code.