A config file is specific to a VPN provider, and each will have its own server address, server certificate, and tls auth information. It can get a little complicated, especially if it's your first time, and most router interfaces aren't very user-friendly. To get help with setup and configuration, you will need to contact the tech support team, which will usually be available 24/7. Otherwise, check out the how-to articles which are available on the VPN website.