Close the report, then click on Query in your open ODB database file. Create a new query. Choose the table or tables containing the data to be extracted and add the fields to the query. In the present example, we have used the DatePurchased and PurchasePrice fields. In the function criteria of your query, choose Group for the DatePurchased field and Sum for the PurchasePrice field.
Save the query and then open your report in Edit mode to change it. Click on the Diagram button in the main toolbar and draw an area with the mouse in the Footer section to contain the chart. In the Properties panel, on the Data tab, choose the query you just created as the data source.