Certain Cmdlets may not be available in earlier versions of Powershell
To check your version of powershell, at the powershell prompt type
Get-Host
or
$PSVersionTable.PSVersion
Download Powershell 4.0https://www.microsoft.com/en-us/download/details.aspx?id=40855
Download Powershell 5.0
Latest version at the time of writing
https://www.microsoft.com/en-us/download/details.aspx?id=50395