To start find out what version is your copy.To do this, start the game itself, bring up the console by pressing the "e" (if the console does not open, go to the keyboard settings and turn on the console).After opening the console, type the word in her version.The same is done and your companions on the game.Remember, your version of the game must be the same.
next step you and your friends need to patch to version Left4Dead or do this, first download the patch from this link (not necessarily take a patch for this link, you can find him on their own).After that download pirated Steam-client called SteamUP, by clicking the link the program
and, if necessary, log in to it.
Then download one additional program - Garena - a platform for games, allowing to create a local network.You can get it on this link downloading, install and run it.If you are prompted to register it, enter your details: username, password and valid email address (it will email confirmation).
After all the manipulations to install and register the necessary programs run first SteamUp, and then - Garena.In the latter, select the desired Left4Dead.You will see several playrooms, a list of which is found Russian and go into it, making the standard two mouse clicks.After that, open the Settings Garena games Left4Dead (button is located under the same name chat), where in the first field, specify the path to the folder with the game, or rather to a file with the extension .exe.In the second field, enter this string:

+ sv_allow_lobby_connect_only 0 + sv_lan 1
After saving the settings, click "Start!" In Garena, thereby starting the game.The menu online game get the line "Local Server" and select any address.