Open the main report in design view, make sure you can see
the section where you want the subreport, then drag the
report you want to use as a subreport from the database
window and drop it in the desired main report section.
Note that a subreport is a special kind of control that just
displays a report object. There are a few things in a
report that are non-functional when displayed in a
subreport, most notably, the page header/footer sections.
