How to add a sub-domain?

It is possible to add a sub-domain (Only if both the websites are located in the same server) but we don't recommend it because there is no way to find out what data came out of what then and it will all get mixed up with the main domain.

What we suggest is to simply add a sub-domain as a website and paste the new tracking code since that will keep all the data & analytics separated or else it will become very difficult to see the page views or visitors of a particular domain.

Check out this quick guide on how to add your website: How to add a website