i can't add a server eventhough i do exactly what i saw on the Youtube. Need help (. Thank you very munch

Adding a CS server is very simple. All you really need to do is make sure you are entering the correct IP and port it is running on, as well as make sure you are allowing traffic on the respective port. That may mean opening a port in your firewall, portforward in your router, whitelist the scanner IPs, or whatever is most appropriate for your network.