Simple reports can be created by selecting Reports, New, selecting the table or query to use, and clicking on the Basic Report icon .
More complex layouts can be created using the Report Wizard. Click on the Report Wizard icon and you will see the fields to choose from. The order you choose the fields will be the one shown in the report, click next, ignore grouping (click next again), now select a sort order (e.g. customer, product or order), click next, select Tabular, next, next and give a Title to the report, and click Finish.
At this point you have your report formatted, but you have no total and sub-totals.
Select the basic report in the left pane, right-click and choose design view. Now add totals to the report: right-click in the design view, select Sorting and grouping and a toolbar will be added at the bottom to do so.
Click on the toolbar to group by a field (e.g. customer number) and choose the field to create totals as in this example.
Save everything. You are mostly done. You can now embellish the report at your hearts content. Use help for more details.