How can i get full game screen i only have 3 quarter of screen when playing command and conquer.?

To achieve a full-screen display in Command and Conquer, first check your game's settings for a "Display" or "Graphics" option, and select "Full Screen" mode. If that doesn't work, you can try adjusting your monitor's resolution to match the game’s recommended resolution. Additionally, ensure your graphics drivers are up to date, as outdated drivers can cause display issues. Lastly, you can also try running the game in compatibility mode for older versions of Windows if you're on a newer system.