Hey Degalbro,
Just for you and a friend?
Awesome, that's fairly simple to get going.
When you start a singleplayer world, it actually creates it as a server too, but people can only join if they know your IP.
Go here to get your IP: http://www.whatsmyip.org/
Now you will need to port-forward on your router (the way you do this varies on which router you use) the ports to forward:
4255-4259 on both UDP and TCP.
If you can find out which router you have, I can give more specific instructions for port-forwarding.
Now just give your friend your IP and they can connect.