This Tutorial is based on the - via (Bit)Torrent - downloadable ISO (Version 2016-10-01) in the download overview (https://www.archlinux.org/download/) and installation via USB.
! Please do not use an older ISO than the possible downloadable listed one at the time of your Arch Linux installation.
Note: This tutorial describes only one way and might not be valid any more for further versions of Arch Linux. There are many other ways how to do it.
Note2: The Arch Linux Wiki is the best documentation I have ever seen so far so I totally recommend it in case of need: https://wiki.archlinux.org/index.php/Main_page