To create a report, you need to specify at least one field to appear in the report. You can accomplish this on the Results tab, which also shows you a sample result set.
Please note you can include aggregate functions to group certain data at this level (or you can leave that to Crystal Reports, if you are designing a Crystal Report).
The important thing to bear in mind here is that if you leave the aggregate functions to Crystal, the query will conceivably retrieve more rows to be filtered later by Crystal. Depending on the volume of data, this could slow down your report.
See Report Fields for more detailed information on each field.