private void AddLessonIndex(int startColumn, int numberofCell)
        {
            for (var i = 0; i < numberofCell; i++)
            {
                var columnIndex  = startColumn + i;
                var lessonHeader = new DCell(1, columnIndex, 1, 1);
                lessonHeader.BackgroundContent = (i + 1).ToString();

                TimeTableContext.AddCell(lessonHeader);
            }
        }
 /// <summary>
 /// InsertBackgroudForAllTimeItems
 /// </summary>
 private void InsertBackgroudForAllTimeItems()
 {
     // row form 2 to end
     for (var i = 2; i < TimeTableContext.Rows.Count; i++)
     {
         // column from 1 to end
         for (var j = 1; j < TimeTableContext.Columns.Count; j++)
         {
             var contentCell = new DCell(i, j, 1, 1);
             contentCell.BackgroundContent = "";
             TimeTableContext.AddCell(contentCell);
         }
     }
 }