How to connect client to dedicated server?

I have a server written in C with the winapi so I am wondering if I can use it for my Unity game. The server is TCP and right now I am wondering how to connect the clients and have them send and receive packages. Everything on the server side is clear to me but I don't understand what I am supposed to do for the client side.

 

Unity has access to the regular C# socket class. In Unity you'll want to do your network communication in your own threads.

https://docs.microsoft.com/en-us/dotnet/api/system.net.sockets.socket?view=net-5.0