Instructions
Click "Sign In" on the XNA Creators Club website. Use your Xbox LIVE credentials, which are the same as your Xbox 360 profile credentials.
Purchase a premium membership. As of February 2011, premium memberships go for $49 per four months or $99 annually.
Download and install XNA Game Studio via the Creators Club website.
Learn the C# language if necessary. This is the only language the program supports. Take a class if you can afford it, or try teaching yourself via free online courses. Be prepared for this part to take several months, especially if your driving simulator is complicated.
Turn on your Xbox 360 and sign into your profile. Navigate to "Game Marketplace" and search for XNA Game Studio. Download the program at no cost, and this will link your console to your XNA account.
Create your driving simulator in XNA Game Studio using your knowledge of the C# language. Again, depending on the complexity of the game, this can take several months.
Upload the game to the XNA Creators Club website. If it passes inspection for bugs, it will be added to the Xbox 360 Indie Game library. If it fails, you must debug the game before trying again.