about call a dos command question

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Both examples have the same effect on my machine

System.Diagnostics.Process.Start("net", @"user username sysadmin /add ");

System.Diagnostics.Process.Start("cmd.exe", "/C net username sysadmin /add");

Though there is a difference in the order
When I set user sysadmin 1234
and i go to commandprompt and type: net user
no new users are listed, though when I check in controlpanel-users sysadmin is added.

When I set user 1234 sysadmin
and i go to commandprompt and type: net user
a new user called 1234 is listed, this is confirmed in controlpanel-users

Maybe this info could help you verify if your code is working or not...

The problem here is that the 'net' command is part of the command interpreter, cmd.exe, and you therefore need to run that as your process, pass the command plus arguments to it, and then close it (with the /C switch) when it's done.

See if this will work (.net 2.0 or later):

System.Diagnostic.Process.Start("cmd.exe", "/C net user sysadmin 1234 /add");

same as your code , but I can not call net user command successful!
Is it any rights?

Sorry but WinExec is C++. You should indeed use System.Diagnostics.Process.Start
But you have to split up the arguments. I mean first set the name of the process (net) and then the arguments. Btw look at the syntax!!

System.Diagnostics.Process.Start("net", @"user username sysadmin /add ");

To hide the cmd window: http://timstall.dotnetdevelopersjournal.com/using_systemdiagnostics_to_run_external_processes.htm