C#

public void FillPoDetails()
       {

           DataTable dt = new DataTable();

           dt = pmdata.createdatatable(int.Parse(Session["OurStyleid"].ToString()), int.Parse(Session["PoPackid"].ToString()));



        GenerateTable(dt.Columns.Count, dt.Rows.Count,dt);

           foreach (DataColumn col in dt.Columns)
           {
               //Declare the bound field and allocate memory for the bound field.
               TemplateField bfield = new TemplateField();

               //Initalize the DataField value.
               bfield.HeaderTemplate = new ArtWebApp.Controls.GridViewTemplate(ListItemType.Header, col.ColumnName);

               //Initialize the HeaderText field value.
               bfield.ItemTemplate = new ArtWebApp.Controls.GridViewTemplate(ListItemType.Item, col.ColumnName);

               //Add the newly created bound field to the GridView.
               GrdDynamic.Columns.Add(bfield);
           }



           GrdDynamic.DataSource = dt;
           GrdDynamic.DataBind();

       }
      public GridViewTemplate(ListItemType type, string colname)
           {
               //Stores the template type.
               _templateType = type;

               //Stores the column name.
               _columnName = colname;
           }

       void ITemplate.InstantiateIn(System.Web.UI.Control container)
           {
               switch (_templateType)
               {
                   case ListItemType.Header:
                       //Creates a new label control and add it to the container.
                       Label lbl = new Label();            //Allocates the new label object.
                       lbl.Text = _columnName;
                       lbl.CssClass = "Headerclass";
                           //Assigns the name of the column in the lable.
                       container.Controls.Add(lbl);        //Adds the newly created label control to the container.
                       break;

                   case ListItemType.Item:
                       //Creates a new text box control and add it to the container.
                       TextBox tb1 = new TextBox();                            //Allocates the new text box object.
                       tb1.DataBinding += new EventHandler(tb1_DataBinding);   //Attaches the data binding event.
                       tb1.Columns =6;                                        //Creates a column with size 4.
                                                                              // tb1.Width = System.Web.UI.WebControls.Unit.Percentage(100);
                       tb1.Width = 100;
                       tb1.Wrap = true;
                       tb1.ID = "txt_" + _columnName;
                       if(_columnName== "ColorTotal")
                       {
                           tb1.CssClass = "ColorTotal";
                       }
                       else if (_columnName == "Color")
                       {
                           tb1.CssClass = "Color";
                       }
                       else
                       {
                           tb1.CssClass = "txtCalQty";
                           tb1.Attributes.Add("onkeypress", "return isNumberKey(event,this)");
                           tb1.Attributes.Add("onkeyup", "sumofQty(this)");
                       }

                       container.Controls.Add(tb1);                            //Adds the newly created textbox to the container.

                       break;


               }
           }

//calculate the sum of qty on keypress
       function sumofQty(objText) {
       
        
           var cell = objText.parentNode;
           
           var row = cell.parentNode;

           var sum = 0;
           var textboxs = row.getElementsByClassName("txtCalQty");

           for (var i = 0; i < textboxs.length; i++)
           {
               sum += parseFloat(textboxs[i].value);
           }
           var textboxtotalqtys = row.getElementsByClassName("ColorTotal");
           textboxtotalqtys[0].value = sum.toString();         

       }

class Program
{
    private static string _address;
    private static string _userName;
    private static string _password;
    static void Main(string[] args)
    {
    }
    // A FileSystemWatcher passes the file name into this method
    public static async void FileReceived(string fileName)
    {
        Task<string> t = await Task.Run(() => FTPFile(fileName));       // <=== ERROR HERE
        await t.ContinueWith((t1) =>
        {
            FileUploaded(t1.Result);
        });
    }
    // FTP the file to the server
    private static string FTPFile(string fileName)
    {
        string remoteFile = Path.GetFileName(fileName);
        SFTP sftp = new SFTP(_address, _userName, _password);
        sftp.UploadFileAsync(fileName, remoteFile);
        return fileName;
    }
    private static async void FileUploaded(string fileName)
    {
        // Once here, the file has been transfered.
    }
}

Cannot implicitly convert type 'string' to 'System.Threading.Tasks.Task<string>'

/* This is a blink label user control --------------------------------*/
public partial class BlinkLabel : Label {

private CancellationTokenSource ts;
private Task task1;

public BlinkLabel()
{ 
   InitializeComponent(); 
}

public void StartBlink()
{
   ts=new CancellationTokenSource();
   CancellationToken ct = ts.Token;

   if ( isRunningTask(task1) ) return;

   task1 = Task.Factory.StartNew(() =>
   {
       while (true)
       {
           ct.ThrowIfCancellationRequested();
           Thread.Sleep(500);
           Visible = !Visible;
                    
       }
    }, ct);

    blinkTask.ContinueWith(t =>
    {
        Visible = false;

    },TaskContinuationOptions.None);

            
}

public void StopBlink()
{
    ts.Cancel();
}

}

/* This is a my main form that use blink label user control--------------------------------*/
public partial class MainForm: Form
{
    public MainForm
   {
       InitializeComponent(); 
      
       blinkLabel1.Text="Blinking message...";
       blinkLabel1.StartBlink(); //Works
       blinkLabel1.StopBlink();  //Not works - blink not stop.
   }
    
}

 try
{
    WebRequest request = WebRequest.Create("http://facebook.com");
    HttpWebResponse response = (HttpWebResponse) request.GetResponse();
    
    MessageBox.Show("I am here!");                
}
catch (Exception ex)
{
    MessageBox.Show("Error Occurred!");
}