How to Open the Boot Menu of a Computer
Many of your computer's settings and system preferences can be enabled or disabled from within the computer's operating system. On Windows-based systems, most options can be tailored from your Start Menu or by opening the "Properties" window. However, some boot options must be accessed from the computer's boot menu, which you can access on all Windows-based computers from the screen that appears at startup.
Turn your computer off.
Turn your computer back on.
Press the "F8" key while your computer boots up. Keep pressing "F8" until the boot menu appears.