The error "cannot find the server" is displayed after adding the domain to you on NS.
If you are correct added domain name record, but it is still unavailable, you need to wait up to 24 hours in order to data updated on all caching DNS-servers of providers.
How to bind a subdomain to ip: port / directory /?
By standard means of the system DNS domain can only be directed to IP. The port and access directory must be configured directly on the web server running on this IP. Alternatively, you can use an intermediate proxy server that will redirect all requests addressed to the domain to the correct IP and port.