To turn on Secure Boot in Windows 10, follow these steps:

1. Check if Secure Boot is already enabled:
   • Press the Windows key, type "system information," and open it.
   • Scroll down to find "Secure Boot State." If it says "Off," proceed to enable it.
2. Open Windows Settings:
   • Click the Windows Start button and open "Settings."
3. Access Advanced Startup:
   • Go to "Update & Security."
   • Click "Recovery" on the left.
   • Under "Advanced startup," click "Restart now."
4. Enter UEFI Firmware Settings:
   • After the restart, select "Troubleshoot" > "Advanced options" > "UEFI Firmware Settings."
   • Click "Restart" to enter BIOS/UEFI.
5. Enable Secure Boot in BIOS:
   • In BIOS, navigate to the "Boot" tab.
   • Find "Secure Boot" and set it to "Enabled."
   • Make sure "OS Type" is set to "Windows UEFI mode."
   • If using Compatibility Support Module (CSM), disable it by setting "Launch CSM" to Disabled to switch BIOS to UEFI mode.
6. Save and exit BIOS:
   • Press F10 to save changes and exit.
   • Your PC will restart with Secure Boot enabled.
7. Verify Secure Boot is enabled:
   • Open "system information" again and check "Secure Boot State." It should now say "On."

Note: Your Windows installation drive must be formatted with GPT partition style, and BIOS mode should be UEFI for Secure Boot to work. If your drive is MBR, you may need to convert it to GPT before enabling Secure Boot. These instructions might slightly vary depending on your PC manufacturer, so refer to your specific device's manual if necessary.