(You may not see the UEFI Settings option on a few Windows 8 PCs, even if they come with UEFI - consult your manufacturer’s documentation for information on getting to its UEFI settings screen in this case.) Select the Troubleshoot option, select Advanced options, and then select UEFI Settings.
Your computer will restart into the advanced boot options screen.
To do this, open the Settings charm - press Windows Key + I to open it - click the Power button, then press and hold the Shift key as you click Restart. To access this screen, you’ll need to access the boot options menu in Windows 8. You can control Secure Boot from your UEFI Firmware Settings screen. See the last section for instructions on booting from a removable device.
You should be able to install current versions of Ubuntu - either the LTS release or the latest release - without any trouble on most new PCs. If you need to boot an older Linux distribution that doesn’t provide any information about this, you’ll just need to disable Secure Boot. You should check to see which process your Linux distribution of choice recommends. This doesn’t seem to be a common at the moment. Add a Signing Key to the UEFI Firmware: Some Linux distributions may sign their boot loaders with their own key, which you can add to your UEFI firmware.This is also necessary if you want to install an older version of Windows that wasn’t developed with Secure Boot in mind, such as Windows 7.
PCs that come with Windows 8 and Windows 8.1 include UEFI firmware instead of the traditional BIOS.