Partitioning Ubuntu with Windows 8.1 Help

So I figured the teks convinced me to install Linux and give it a shot especially with the anonymity features that can be accessed. I want to do a Dual Boot with Windows 8.1 but the installer doesn't register I have a OS already installed. Can anyone give me a detailed step-by-step partitioning guide and/or pm me your skype and help me as I go. I have 1TB HDD with around 400 Gb free.

Its because of the uefi that comes with windows 8. I know this isn't a Tek community guide but it covers the basics of what you need to do. Enjoy!

Guide from the interwebs

Edit: I assumed you are installing Ubuntu(lol), anything Debian based will require the same process as the guide above, with the exception of the boot manager path and the theme of the installer.

This is bit will be need to be adjusted to suite your distro.

bcdedit /set "{bootmgr}" path \EFI\ubuntu\grubx64.efi