To track how your site is performing, you can turn on a third-party tool like Google Analytics. To use an analytics tool, you can set up Google Tag Manager under Site Settings.
Setup Google Analytics with your website URL, and keep track of the measurement ID. It will start G-XXXX.
Go to Google Tag Manager, create a container for your website, then choose "New Tag". Choose Google Tag as the tag type.
Fill in your measurement ID from above as the tag ID. Make sure to include the G- in the tag ID.
Make sure that the tag is set to trigger for all pages, and don't forget to publish it.
Copy your new GTM- tag ID into gamma. This is not the measurement ID that starts with G- , but the tag manager ID that starts with GTM-.
We recommend the following Google help articles to learn more: