VOMP

To Host Server when in game

Use the "Tab" key to bring up the console and inside it type "Host"

To Join Server 

Use the "Tab" key to bring up the console and type "Join" followed by the Host's IP address. E.G (Join 12.34.56)

How to find your IP address.

Open up CommandPropt and type "ipconfig" then copy the "IPV4 Address". (This is the IP address you need).

Lan is the only online mode supported