In the Blur game main menu go to:
4.1 Multiplayer
4.2 Local area networks
4.3 Here you will see the list of games, if you don’t see any – start your server and wait when people will connect
To Host your game press “Ctrl” key on your keyboard while in the menu from the 4c point -> Choose “Custom game” and wait for others to join
Troubleshooting
If you can't see your friends or any servers in the game:
make sure you all have the same game version
make sure you did all the steps in the instruction above