After adding a chart to your project, double-click it to access the data table, or select it once to access the settings for in the right sidebar. Use tabs at the top to switch from one to the other.
By default, each chart is populated with sample data as a formatting guide for your data. If you plan to import data from an external data source, keep this formatting and adjust your data source accordingly for the best results.
To learn more about how to visualize your data, head over to the article on Adding data to a chart.