Session session = new Session();
session.Connect(...);
ProcessManager wfManager = ProcessManager.GetInstance(session);
ProcessLaunchParameters parameters = new ProcessLaunchParameters();

// This creates an XmlDocument to be passed into the launch as the initial values
// for process input variables.  See the documentation for InputDocument for the example
// code for CreateInputXmlDocument().
parameters.InputDocument = CreateInputXmlDocument();
try
{
    ProcessInstance instance = wfManager.LaunchProcessByName("Sample Process Launch", parameters);
    if (instance != null)
    {
        Console.WriteLine("Process started Id: " + instance.NumericId);
    }
    else
    {
        Console.WriteLine("Failed to start process. LaunchProcessByName returned a null instance.");
    }
}
catch (Exception exception)
{
   Console.WriteLine("Caught an exception while starting the process: " + exception.Message);
}