First, you need to install PowerShell version 2.
Log in to the server machine, start PowerShell as an administrator and execute:
Enable-PSRemoting
Answer Y to all questions.
By default PowerShell can't connect to arbitrary hosts. You need to allow that. Here are the commands:
cd WSMan:\localhost\Client
Set-Item TrustedHosts *
Restart-Service WinRm
This one says that we can connect to (trust) all hosts (*).