First, you will need to install X server and Git (as root)
pacman -S xorg-xinit xorg git
Change directory to /usr/src because you want this to apply to all users:
cd /usr/src
As root, clone suckless software such as dwm (window manager), st (recommended terminal), and dmenu (simple application menu)
git clone git://git.suckless.org/dwm
git clone git://git.suckless.org/st
git clone git://git.suckless.org/dmenu
Change directory into each one, and compile them:
cd dwm ## Do this step also with st and dmenu
sudo make clean install
Add a new user that is under the users group (as root):
useradd -m -g users ari
passwd ari
Log out, log in as new user, and execute:
<favorite text editor> .xinitrc
from there, add "exec dwm" into the file, save, and exit
Start your session with:
startx