To add a chart to your report, select Insert > Chart to open the Chart Expert and locate and select the category at the bottom of the list of chart types.

Next, use the data tab to specify where you want to place the chart, as well as the layout and data for the chart. If you have based your chart on a group and summary field you can use the chart to drill-down and you have the same formatting and display options as other chart types (bar, line, etc.)