For example.
You want to add domain.com, means on your machine you want a site to open when you access http://domain.com
So you will create a domain as domain.com with its path. And in advance settings you will check "Add the entry to host file" [Ignore the warning in red temporary as it is required to configure the host file]
Since AMPPS was not able to add the entry(as mentioned in the warning). Open hosts file and write.
127.0.0.1 domain.com
Now from your machine you can access http://domain.com and the site will open according to the path you have specified for the domain.