The lobby is a place where you make your own team to invite your friends. If none of your friends are active, you can fight your own (meaning other people will join). You have the number of three choices:
1. Do a public match
2. Make a private match
3. Browse
Public Match[]
In public match, it you can invite your friends and choices are your following. You can do Team Death Match, Death Match, or Bomb Defusal. It depends on how much you invite your friends. If not much, then other players will have to join.
Private Match[]
It is your choice to escort your friends by teams. If your the only one in the lobby, then, you can’t do it. You have five places to select and choose one. If you don’t want to choose any, then it will be random.
Browse[]
This button is where you join in to another lobby. There is possible that there is no new match so you have to make or play a new one.