^ Networking Basics
^ Multiplayer HUD tutorial
^ Should help with the basic match making/ networking side of things.
Mate, this took me a grand 15 seconds to google search and paste the results, look before you ask questions. Also keep in mind that based on your lack of googling skills this task of creating a multiplayer game (which is very complicated) may be beyond your level of skill for the time being.
Remember to familiarize yourself with whatever engine you are using, and learn its ins and outs before attempting to create a project, specially one as big as this one.