If you haven't yet been able to play a multiplayer game then:
Open a Finder window.
Do shortcut: Command + Shift + G
Copy/Paste this: ~/Library/Preferences
Hit enter & it should bring it up for you.
The actual path is Users/yourusernamehere/Library/Preferences.
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Just thought I'd add (if you don't already know), since your having trouble finding it.
When your in the Preferences folder, click on empty space anywhere in the window and type com.aspyr
Should take you straight to it.