How do I play a multiplayer game in GRID 2 Reloaded Edition on Steam?

How you play an online multiplayer game in GRID 2 Reloaded Edition differs depending on whether you wish to host or join the game.

To host:

From the Main Menu, select GRID Online.
Select Events.
Select Online.
The Online Party Lobby will appear. Select Online Custom Event.
Select Create Game.
A dialog will appear asking you whether you wish to allow players to use downloadable content. Select your preferred option. If you select Yes, players who do not own DLC being used in the game may not be able to join the game.
The game options screen will appear. From here, you can customize the game settings. When you are happy with your settings, select Done.
To invite friends from your Steam friends' list to the game, select Invite Friends. Otherwise, proceed to step 10.
The Choose Friends to Invite dialog will appear. Click the Invite button next to the name(s) of the friend(s) you wish to invite, then select Return to Game.
When you are happy with your settings and the other players have joined the game, select Start.
The car selection screen will appear once all the currently connected players have indicated that they are ready or after 15 seconds, whichever is the sooner. Select a car.
The game will begin once all the currently connected players have selected a car or after 20 seconds, whichever is the sooner.

To join:

From the Main Menu, select GRID Online.
Select Events.
Select Online.
The Online Party Lobby will appear. Select Online Custom Event.
Select Custom Match.
Use the filters to select the type of game you wish to search for, then select Search.
A list of games matching your criteria will appear. Select the game you wish to join.
The lobby will appear. To invite friends from your Steam friends' list to the game, select Invite Friends. Otherwise, proceed to step 10.
The Choose Friends to Invite dialog will appear. Click the Invite button next to the name(s) of the friend(s) you wish to invite, then select Return to Game.
Select Ready Up.
When the host starts the game, the car selection screen will appear. Select a car.
The game will begin once all the currently connected players have selected a car or after 20 seconds, whichever is the sooner.

NOTE: Additional players can join the session while the game is in progress, but will not be able to take part until the next game begins.