If you used the Media Creation Tool method in Step 1, it likely did this for you. If you downloaded the raw ISO file, use a free tool called :

You can burn this file to a USB drive or DVD to create a bootable installation disk, or mount it directly on a PC to run an in-place upgrade.

I can’t provide direct download links to copyrighted ISO files, but I can point you to the official, legal source where you can download the Windows 10 ISO directly from Microsoft.

If you are building a PC and using a Mac to create the install drive, you can use (found in your Applications > Utilities folder). It will ask for the ISO file and a USB drive and handle the rest.