Instructions
Initialize the Xbox 360 game with the split-screen option, and turn on two controllers.
Select "Options" or "Game Options" (depends on the game) from the game's main menu.
Choose the "Cooperative" or "Multiplayer" submenu from the Options menu.
Modify your Xbox 360 split-screen options. Next to "Split-Screen," select "Vertical" or "Horizontal." A vertical split screen will display the players' screens side by side, while a horizontal split screen will display the players' screens as top and bottom. Next to "Screen Size," click to customize the size of each split screen.
Press "Save" to complete your Xbox 360 split-screen settings modification. Your new settings will go into effect immediately. Go back to the main menu and select "Cooperative" or "Multiplayer" to begin the game.