Adding CNAME record for a domain with subdomain
In this case your custom domain will look like
calender.yourbusiness.com
Log in to your Namecheap dashboard and go to Domain List
Click on Manage button for your domain in the list
Go to Advanced DNS
Click on Add record
Select CNAME as the Type
Add Host and Value
Copy the values from the custom domain page and add
Click ✅ button
For more information refer official documentation
Adding ALIAS record for a root domain
In this case your custom domain will look like
yourbusiness.com
Follow the same steps mentioned above except selecting the record type
Select ALIAS as the Type
For more information refer official documentation