Run the MediaCreationTool.exe file once it is finished downloading.
Select Create installation media for another PC.
If you want a language, edition, or architecture (32-bit vs 64-bit) other than the automatic settings then deselect Use recommended options for this PC and edit the settings as necessary.
Select USB flash drive then hit next.
Select the drive that you want the tool on and then select finish.
On the computer that you wish to have windows 10 on, plug in the USB and restart the computer, booting to the USB. (If you do not know your computer's boot menu key check the Booting to the Boot Menu and BIOS page)
Follow the prompts to finish upgrade to windows 10.