The syntax would be:
C:\Documents and Settings\sharmall\Desktop\shutdown\shutdown.exe /l /t:300 "The computer is shutting down" /y /c
l (lower case letter "l") - local computer
t:300 - in 5 minutes
y - "yes" to all computer questions
c - quit all running programs
Save the above line as a batch file, and you're done.
P. S. I'm not an expert here, but it should work. If I'm incorrect, please, someone chime in.