The PowerShell here just wraps the RoboCopy functionality. Code.
But if you just want to keep it real simple, for a basic do-it-all backup, do this…
Robocopy.exe c:\temp d:\tempxxx /E
, where c:\temp is the root/source directory to copy, including subfolders, d:\tempxxx is the target directory, which does not need to exist when you execute the copy, and /E says “also create any empty folders you find in the source.