This is so much simple, you just have to follow the steps below:
 
1) Enable console in Game Settings.
2) Type in console "sv_lan 1".
3) Type "map de_aztec" for example or any map you want.
4) Go to Browse Community and click in LAN.
5) Invite whoever you want to join and play with you in the LAN menu.
6) Refresh.
7) Enjoy. 
 

 
Or if you want, this video explains how to do it.
 

MoNeYinPHX

Note: Not necessarily to play LAN you need to use Tunngle. You can also play LAN using any method you see fit, as an example, the above method. But if you still prefer to use Tunngle, you should follow the methods below:
 
 

How to play LAN using Tunngle.
 
#      Sing up an account for free. You will should go here.
#      Download and install Tunngle. You will get Tunngle client here.
#      After done this, open Tunngle client.
#      Login Tunngle, search for Counter-Strike Global Offensive in Network Search and join Counter Strike Global Offensive channel. After this the room will open.
#      Now, open CSGO game to create a server:
- Enable console in Game Settings.
- Create any game with or without bots.
- While the game, type without quotes on console, "sv_lan 1", "bot_quota X" in which X represents the numbers and the number 0 play without bots and "status" is where you will pick up your IP address.
- After showing the status. Copy your IP in the TCP / IP Line, example "1.22.333.444:27016".
- To play in your game should be typed on console, without quotes, "connect 1.22.333.444:27016" (in place of the fictional IP, you should put your IP in place). This is also valid to your friends connect. 
- After done all this, give your IP to your friends to join in game or invite to Tunngle room.
 
If that doesn't work, you will probably need the SmartEmu in which you should probably find the patch here.

 

Have Fun!

More people must join to tunngle..

Sorry but i am not think this works :/ .I tried with my frnds they can't see my server on lan and even they can't connect also. (p:s: Me and my friends are using same patch)