Need TCP help

I am new to Java, but not new to programming, having been previously a Delphi, then C# developer.

I need to write a utility that will send messages to, and receive messages from, another machine on the network via TCP.

I will load the messages to send from a file, looping through the file a line at a time.

If it makes a difference, I'm using Windows XP as my dev machine.

Two ways I know to communicate over the internet: Sockets and Datagrams.
No idea where or if TCP fits into these.

Suggested reading:
Lesson: All About Sockets (The Java™ Tutorials > Custom Networking)
And yes, TCP fits into Sockets.