There are several methods to begin your Gameplay. You can Find Match, Horde Mode, Create Room or Browse Lobby.
Play -> Practice -> Choose options
The Practice match is only against bots and will not count towards Achievements.
For those players just starting out, it is recommended to stick with a single map so that you can learn the locations of the guns, moonshine pots, power-ups and general layout. When you are comfortable with one, move on to the next.
Play -> Find Match
The Find Match button will automatically join a room that is available on your server. If none are available, it will create a new room with a 7 minute time limit, a maximum of 7 bots on a random Map and Game Mode.
Play -> Horde Mode
The Horde Mode button will automatically join a horde mode room that is available on your server. If none are available, it will create a new room on Wave 1 of Horde Mode.
Play -> Create Room -> Choose Options
Create Room will allow you to customize a game. Once that game is over, a new game with the same options will start. In order to change options, you will need to exit the game and return to the Create Room again.
A room name will be automatically generates for you. You can select 1 Map, 3 Maps or all of them, each consecutive game will randomly play in whichever map options you have chosen. You can choose to play one Game Mode repetitively or have it random for each consecutive game. The number of players allowed in a room is 2-10 while the number of bots is 0-9.
You can add a password onto a room if you'd like to keep a match private between yourself and selected friends. HOWEVER! Password-protected rooms are not eligible for Steam Achievements and will not grant experience.
Play -> Browse Lobby -> Choose room created by other players
Any player-created rooms are available for public viewing in this Lobby. You can join any server, however for the best experience, it's recommended to join the region closest to you. The regions available are: Australia, China, Europe, India, Japan, Russia, South America, US East and US West.
Details of the Game Mode, Player Count (not bots), and Match Duration are all available for viewing. Rooms that are password protected will be notated and you will be unable to join unless you know the password. You can't join the chat of a room to ask for the password either. However, you can check out the Discord as many private game rooms are generated from players meeting up there.