1. Install Radmin VPN
2. Create your Network by clicking on a "Create Network". Set up Network name and Password
3. Share network name and password with your friends. 
4. Your friends need to join your network by clicking on a "Join Network" in Radmin VPN.
5. Make sure that you all are in the same Radmin VPN network, have the same C&C: Generals version.
6. Go to Options from the main menu and check, that Online IP and LAN IP is the same as IP in Radmin VPN - starting with 26
   
   

Here is also a guide on how to create and manage the network.

How to cre ate server in LAN for C&C: Generals - Zero Hour online

How to join the server in LAN C&C: Generals - Zero Hour online

1. Make sure you did all the steps in Setup section
2. In the game go to Multiplayer menu from the Main menu
3. Then to LAN
   
4. Here you should see the lobbies created by hosts, join the one you like 
5. Press Accept and wait till the lobby creator will start the game
   

How to find teammates for coop online

Troubleshooting