Probably you may not be able to start a match if you not played multiplayer before. In this case, you need Level 2 in public games to get Cod points. After this you can create a private game in wager match

1) Enable the console in the game settings.
2) Choose: Play -> Wager Match and get "could not join match" error
3) Open console with "~" and type \g_gametype gun first then \map mp_array
4) Start a match and use these 2 commands: /party_minplayers 1 (This enables the game to start with just 1 player) and /scr_gun_timelimit 0.1 (This reduces the game time to 10 seconds for fast rounds)
5) Once you've typed these commands, restart the map using /map_restart for the above commands to take effect.
4) To get the achievement you must be in the top3 for 5 games. The achievement pops after you wait out 5 rounds.

*Thanks WantedWolf to this method

1) Enable the console in the game settings
2) Choose: Play -> Wager Match and get "could not join match" error
3) Open console with "~" and type \g_gametype oic first then \map mp_array
You will start a match, after which you need 1 friend to play with. Your friend can join through the "Friends" tab in the right corner of the main screen.
4) To get the achievement you must be in the top3 for 5 games. Two players get achievement after completing the last match.

https://youtu.be/Eznacpbu-64

If you want to play other modes, you can also play them. Below I will provide a list of commands for various modes and maps.
One in the chamber
\g_gametype oic

Sticks and Stones
\g_gametype hlnd

Gun Game
\g_gametype gun

Sharpshooter
\g_gametype shrp

Original maps
\map mp_array
\map mp_cairo (havana)
\map mp_cosmodrome (launch)
\map mp_cracked
\map mp_crysis
\map mp_duga (grid)
\map mp_firingrange
\map mp_hanoi
\map mp_havoc (jungle)
\map mp_mountain (summit)
\map mp_nuked (nuketown)
\map mp_radiation
\map mp_russianbase (WMD)
\map mp_villa

\map mp_berlinwall2 (Berlin Wall)
\map mp_discovery (Discovery)
\map mp_kowloon (Kowloon)
\devmap mp_stadium (Stadium)

\map mp_gridloc (Convoy)
\map mp_hotel (Hotel)
\map mp_outskirts (Stockpile)
\map mp_zool (Zoo)

\map mp_drivein (Drive-In)
\map mp_area51 (Hanger 18)
\map mp_golfcoursel (Hazard)
\map mp_silol (Silo)