The Game1 class has a simple constructor with no parameters. An instance of this class will be created by the shell contained in the Program.cs file within the project when the game is launched.
Note
The Program.cs file
When your XNA game starts, the Main() method in the Program.cs file is what actually gets executed. This method creates an instance of your Game1 class and calls the Run() method, which performs the initialization we will discuss shortly. It then begins executing the game loop, updating and drawing your game repeatedly until the program exits. In many games, we will not have to worry about Program.cs, but there are some instances (combining XNA and Windows Forms, for example) when it is necessary to make changes here.
By default, the constructor has created an instance of the GraphicsDeviceManager class to store in the graphics member, and has established the base directory for the Content object, which is an instance of the ContentManager class.
When we build our project, all of the items in the content project are translated into a format specific to XNA, with the .xnb file extension. These are then copied to the Content folder in the same directory as our game's executable file.
Our Speller game will not need to make any changes to the class constructor, so we will simply move on to the next method that is called when our game starts.