The Tutorial shows you How to Install and SetUp the KDE4 Linux Desktop on Arch-Linux 2012.10+ with Systemd Kdm Management.
All Steps are Clearly Delineated Reducing at Minimum the Eventuals Choices and Customizations to Make Clearer & Easier the Process.
After if you Have Some Doubt or Need Some More Insight you Should Consult the Official Online Arch-Linux Documentation…
Just Relax & Take the Time of Carefully Reading and Executing the Instructions Contained Here and All should Work Like a Summer Breeze :)

Prerequisite for KDE4 is the XOrg Server Installation & SetUp:
XOrg Installation Arch-LinuxInstalling the Latest KDE4 Desktop
pacman -Sy kde
Arch-Linux Troubleshooting pacman “Could Not Resolve Host”:
Dhcp Internet Network SetUpEnabling Login Into KDE4 at Boot
systemctl enable kdm.service
systemctl start kdm.service
Reboot Directly Into Arch-Linux KDE4 Desktop .)
Here is the Complete Guide for Installing Arch-Linux 2012.10 + KDE4: