The Google Tag Manager allows you to manage tags or snippets of JavaScript that are on your website.
To access and add Google Tag Manager:
Log in to your Google Tag Manager account.
Create an account. Enter an Account Name and select a Country.
Enter your website's name in the Container name text box and select Web as the target platform.
Click Create.
Click the check box to accept the terms of service, then click Yes.
Close the pop-up window and copy the GTM code at the top of the page.
Go to Settings > Google Tag Manager under SEO.
Paste the code in the Container ID box.