Youtube is your best friend :) there are a ton of good simple guides for ARMA 3 and Epoch. Also try doing the ingame tutorials you will learn a lot of the game mechanics and controls. From there get a Microphone all of PC gaming is made 10xs funner and easier when you have a microphone for comms. You will make friends quicker, get answers to questions faster in game and generally have a better experience when playing PC games if you have a microphone for comms.
youtube/google everything you ever want to know and if all else fails ask the questions on forums.
Welcome to REAL online gaming. PC gaming > console gaming IMHO, glad you decided to give it a go.
