You can drag and drop fields from the list on the left into the Sum/Print box on the far right. This adds that column to the report, but not as part of the sort sequence. By default, the “Sum” tab at the top of the Sum/Print box is selected, meaning that the value of the columns in that window will be summarized on the report. If you want to see the details, click the “Print” tab.
NOTE: if you are using Firefox, drag and drop won’t work. You can still use Firefox, but to get columns into the Sum/Print box, select the field in the list at left, then click the “Add” button above the Sum/Print window. (it has a little plus sign.)