How do you pass variable between classes/threads

namespace Phoenix
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>

        public string Start = "Attempting to start ";
        public string Stop = "Attempting to stop ";
        public static TimeSpan timer1 = new TimeSpan(0, 2, 0);

        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
		
        public static void GEN_Start(string location)
        {
            ServiceController svc = new ServiceController("Service Name", location);
            svc.Start();
            svc.WaitForStatus(ServiceControllerStatus.Running, timer1);
            if (svc.Status == ServiceControllerStatus.Running)
            {
				// Service Running do stuff
            }
            else
            {
				// Service not Running do stuff or time-out
            }
        }
    }
	
	public partial class Form1 : Form
    {
        public Form1()
        {
            ConnectionOptions options = new ConnectionOptions();
            options.Password = "username";
            options.Username = "password";
            InitializeComponent();
        }
		private void button4_Click(object sender, EventArgs e)
        {
			// Check if user is sure
            Form2 frm = new Form2();
            DialogResult result = frm.ShowDialog();
            if (result == DialogResult.Yes)
            {
				// Start thread
                Thread START=new Thread(new ThreadStart(Program.GEN_Start(button4.Text)));
                START.Start(button4.Text);
            }
        }
	}

	public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            // YES
        }

        private void button2_Click(object sender, EventArgs e)
        {
            // NO
        }
    }	
}