Asynchronous Method call

    // Class that contains event and event handler
    public class Task
    {
        public delegate void UpdateStatusEventHandler(string text, int total, int current);
        public delegate void UpdateTextEventHandler(string text);
        public delegate void UpdateProgressBarEventHandler(int total, int value);

        public event UpdateStatusEventHandler UpdateStatus;
        public event UpdateTextEventHandler UpdateText;
        public event UpdateProgressBarEventHandler UpdateProgressBar;
    }

handle this class events on Window Application forms. For that you haveto register this events:

            //Write this code on form load or form's constructor
            Task task = new Task();
            task.UpdateProgressBar += new Task.UpdateProgressBarEventHandler(task_UpdateProgressBar);
            task.UpdateStatus += new Task.UpdateStatusEventHandler(task_UpdateStatus);
            task.UpdateText += new Task.UpdateTextEventHandler(task_UpdateText);

now define delegates on form that handle this events asynchronously.

private delegate void delUpdateStatus(Label lbl, string text, int total, int current);        
        private void mUpdateStatus(Label lbl, string text, int total, int current)
        {
            if (lbl.InvokeRequired)
            {
                lbl.BeginInvoke(new delUpdateStatus(mUpdateStatus1), lbl, text, total, current);
            }
        }

        private void mUpdateStatus1(Label lbl, string text, int total, int current)
        {
            lbl.Text = string.Format("{0}/{1}\n {2}", current, total, text);
            lbl.Update();
            lbl.Parent.Update();
            this.Update();
        }

this way you can update label text asynchronously.

and at last write down method that calls when Task classevents fired

      private void task_UpdateStatus(string text, int total, int current)
        {
            eUpdateStatus(lblStatus, text, total, current);
        }