You’ve added the namespaces to your source file(s) which only really save you from having to type the complete, long winded, NetworkCommsDotNet.Connections.TCP.<whatever> whenever you want to use <whatever>.
But, you don’t appear to have added a reference(s) to the NetworkComms libraries. This is the part that actually tells the compiler that you want to use the library.
Right click the references in your project and then on the window that appears click the browse button near the bottom. Then browse to the folder you unzipped the NetworkComms files to. In there you should find a DLL’s folder and within that you should see folders for different versions of .Net.
I’ve been using the Net40/Merged/NetworkCommsDotNetComplete.dll one, but you can use the individual ones, just make sure you include all you need.