Q: Partition of Drive

Please start at How to install Windows using Boot Camp - Apple Support .

The following links should also help.

Use Windows 10 on your Mac with Boot Camp - Apple Support

https://help.apple.com/bootcamp/assistant/6.0/

You can also download an ISO (DVD Image) of W10 from Microsoft - https://www.microsoft.com/en-us/software-download/home . This will make it easier to create an Installer that the Mac can use.

What year/model is your Mac?

Your Mac supports Windows installation only via the built-in Optical drive. You will not be able to use a USB.

Have you modified Bootcamp Info.plist? Can you check the the model in About This Mac? Do not post the serial number of your Mac.

If you do see a Create USB Installer option, then you can use it. There are a handful models from 2011-12 with built-in Optical drive, which will also support a USB installation.