new upgraded windows 10 - how to make a bootable USB?

Greetings.
My gamer Laptop (ASUS G55VW ROG) is now upgrated from Windows 7 SP1. It went smooth and without errors :)

Before fiddle around too much I want to make a bootable USB-key with Windows 10 installaion to make a clean install possible if I mess windows up so it can't boot.
But how do I make this bootable USB-key? I know I can "reset" the PC from "settings", but that only works if it can boot .

I had the understanding, that it would be possible to make a DVD or an USB-pen to make a clean install?

Anybody know how to do that?
And what about cd-key when cleaninstalling from that bootdevice?

Thank you. Hope Danish is selectable in this media creationtool

Just about every language on the planet was in the list I saw. The steps listed in the link mirror the ones posted by Microsoft on their support page for the process.

Personally, I just used the Media Creation tool and it made the bootable Flash drive with 3gbytes of Win10 on it no problem.