cell = cells.get("B2");
cell.setValue(20);
cell = cells.get("B3");
cell.setValue(50);
ChartCollection charts = sheet.getCharts();
// Adding a chart to the worksheet
int chartIndex = charts.add(ChartType.PYRAMID,5,0,15,5);
Chart chart = charts.get(chartIndex);
// Adding NSeries (chart data source) to the chart ranging from "A1" cell to "B3"
SeriesCollection serieses = chart.getNSeries();
serieses.add("A1:B3", true);