Set wn = WScript.CreateObject("WScript.Network"

Set fs = CreateObject("Scripting.FileSystemObject"

Set ws = CreateObject("WScript.Shell"
SystemRoot = ws.ExpandEnvironmentStrings ("%SYSTEMROOT%"
TxtFile = (SystemRoot & "\somefile.txt"

BakFile = (SystemRoot & "\somefile.bak"
fs.CopyFile TxtFile, BakFile
This script copies thr file %SYSTEMROOT%\somefile.txt (if windows was installed at c:\winnt then the this would be c:\winnt\somefile.txt) to %SYSTEMROOT%\somefile.bak
The Syntax for the copyfile method is fs.CopyFile Varible1, Varible2
The varibles need to be file paths or you will get an error.
Hope this helps.