1. LAN

If it is in the same cafe
First screen left running enter ipconfig
To find the IP address of the IP behind a remember
Then enter the game press the TAB above "~" key exhaled console
Then play the map + space choice map enter start
Let your friends also enter the exhaled console game
Enter the connect + IP address (that is, you just remember that) enter
You can play with the

2. Network online

Make sure find its way to survival version 2 folder open left4dead2 folder
Find the steam file open to see behind the first row 4 digits
You and your friend's version must be the same as if you are not
It is ok to change to the same
And then into the holdfast platform to find a room
After entering the game according to the above steps exhaled console
Enter the map + space choice levels enter
Your friend can see your room is a room in your name
To join the game can play together...