Formatting my PC and installing Windows10. 2 Questions?

[Shadow Slasher]

So I download Windows 10 as an ISO file. Should I extract it to my USB? Or paste it as an ISO file?
Also, I have 2 disk partitions (D and C). Will the Windows 10 installation erase all of my data on both of them, or just one of them? Thank you !
EDIT: what other things do I need to keep in mind before formatting on my own?

 

[SchizTech]

1. The iso has to be extracted and the contents copied over. Also, the USB drive has to be marked as bootable. There are utilities that can do it for you. If you don't mind waiting for another download, run the Windows 10 upgrade assistant and choose the option to create a bootable flash drive, select the drive you want to use to make the installer from and it will do the rest for you.

2. The installer will format only what you tell it to. In fact you can do an upgrade over C without formatting (the existing Windows folder will be moved to "Windows.old" and the user files will remain in the old user directory under Windows.old)

 

[USAFRet]

So I download Windows 10 as an ISO file. Should I extract it to my USB? Or paste it as an ISO file?
Also, I have 2 disk partitions (D and C). Will the Windows 10 installation erase all of my data on both of them, or just one of them? Thank you !
EDIT: what other things do I need to keep in mind before formatting on my own?

The easiest way to create a bootable USB media for Win 10 is with the aptly named "MediaCreation tool"
https://www.microsoft.com/en-us/software-download/windows10

 

[SkyNetRising]

I'd say - the easiest way to create a bootable USB media for Win 10 from ISO file is with Rufus.
Media Creation tool will force you to re-download Win10 installation again.
https://rufus.akeo.ie/