private static void DecorateSlideThree(PPT.Slide slide)
        {
            var columnsList = new string[] { "C#", "VB.Net", "Perl", "Python", "Java" };

            var series1 = new ChartSeries()
                              {
                                      name = "Blog Statistics",
                                      seriesData = new string[] { "8200", "3900", "890", "300", "3278" },
                                      seriesType = XlChartType.xl3DColumn
                              };

            var chartData = new List<ChartSeries>() { series1 };
            var chart = PptChartManager.CreateChart(XlChartType.xlColumnStacked, slide, columnsList, chartData);

            var chartTitle = new ChartTitle()
                                 {
                                         bold = true,
                                         italic = false,
                                         fontSize = 40,
                                         titleText = "Users by Software Language",
                                         underline = false
                                 };

            PptChartManager.AddChartTitle(chart, chartTitle);
            SetSlideFooter(slide, 3);
        }
        public void AddSeriesToExistingChart(PPT.Chart chart, ChartSeries series)
        {
            var workbook = (EXCEL.Workbook)chart.ChartData.Workbook;
            workbook.Windows.Application.Visible = false;
            var cellNumber = 1;

            var dataSheet = (EXCEL.Worksheet)workbook.Worksheets[1];

            var sc = (PPT.SeriesCollection)chart.SeriesCollection();
            var seriesCount = sc.Count;
            var letter = IntToLetters((seriesCount + 2));

            foreach (var value in series.seriesData)
            {
                var cellPosition = letter + cellNumber.ToString();
                dataSheet.Cells.Range[cellPosition].Value2 = value;
                cellNumber++;
                chart.Refresh();
            }

            // we have to populate the sheet with new values, now we need to create a series for it!
            var columnsRange = dataSheet.UsedRange.Columns;
            var rowsRange = dataSheet.UsedRange.Rows;

            var columnCount = columnsRange.Columns.Count;
            var rowCount = rowsRange.Rows.Count;
            var lastColumnLetter = IntToLetters(columnCount);

            var newSeries = sc.NewSeries();
            newSeries.Name = series.name;
            newSeries.XValues = "'Sheet1'!$A$1:$A$" + rowCount;
            newSeries.Values = "'Sheet1'!$" + lastColumnLetter + "$1:$" + lastColumnLetter + "$" + rowCount;
            newSeries.ChartType = series.seriesType;

            chart.Refresh();
        }