Paket installation:

  pacman -S $name    

Pakte suchen

  pacman -Ss $name    

Update Sources

  pacman -Sy $name

Remove a Packet

  pacman -R $name

Install multiple from a package Group

  pacman -S gnome
  Enter a selection (default=all): 1-10 15

Upgrade

  pacman -Syu    

Installation

create boot and root partition, you may olso use lvm, but makes no sense for / on laptop. 
mount /mnt /dev/sa1
mkdir /boot ,
mount /mnt/boot /dev/sda2
... 
pacstrap /mnt base base-devel wpa_supplicant 
genfstab -U /mnt >> /mnt/etc/fstab
arch-chroot /mnt
echo archtux > /etc/hostname
echo LANG=de_DE.UTF8 > /etc/locale.conf
echo LC_COLLATE=C >> /etc/locale.conf
echo LANGUAGE=de_DE >> /etc/locale.conf
echo KEYMAP=de-latin1 > /etc/vconsole.conf
echo FONT=lat9w-16 >> /etc/vconsole.conf
ln -s /usr/share/zoneinfo/Europe/Berlin /etc/localtime
vi /etc/locale.gen
locale-gen
pacman -Sy
mkinitcpio -p linux
passwd
useradd $user -m -d /home/$user
passwd $user
mkdir $user
chown $user:users $user/
pacman -S grub
grub-mkconfig -o /boot/grub/grub.cfg
grub-install /dev/sda
cp /etc/netctl/examples/ethernet-static /etc/netctl/enp0s?

If you have an Intel CPU:

pacman -S intel-ucode 

Install xorg, plasma and KDE:

  pacman -S xorg xorg-xinit xorg-server-utils
  pacman -S plasma kdebase
  pacmna -S ttf-freefont
  pacman -S net-tools gtkmm
  systemctl enable sddm
  pacman -S net-tools gtkmm 
  pacman -S networkmanager
  systemctl enable NetworkManager  

If running in Virtualbox, add:

  pacman -Sy virtualbox-guest-utils
  pacman -Sy linux-headers    

Problems with Sound:

[root@tuxvm user]# pacman -Ss alsa
extra/alsa-firmware 1.0.29-1
  ALSA firmware package 
extra/alsa-lib 1.1.2-1 [Installiert]
  An alternative implementation of Linux sound support
extra/alsa-oss 1.0.28-1
  OSS compatibility library
extra/alsa-plugins 1.1.1-1
  Extra alsa plugins
 extra/alsa-tools 1.1.0-2
  Advanced tools for certain sound cards