ProcessStartInfo info = new ProcessStartInfo(fileName);
info.Arguments = args;
Process process = Process.Start(info);

 [STAThread]
        static void Main([color=red]string[] args[/color])  //string[] args - added by me!!!
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }

private void buttonTest_Click(object sender, EventArgs e)
{
       MessageBox.Show(args[0]);       // Error The name 'args' does not exist in the current context	
}

string[] args = Environment.GetCommandLineArgs();

[STAThread]
        static void Main(string[] args) 
         {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1(args));
        }

public partial class Form1 : Form
    {
        public string arg1;

        public Form1(string[] args)
        {
            InitializeComponent();
            arg1 = args[1];
        }
.............................................