When you choose a field, it is dropped in the header section. There, in the reports it will list the name of the field, such as "Birth date". You can leave it there but, if you want it in the body place the mouse cursor on the field and press the left button and drag it down into the body of the report.
You can select the same field twice, once for a header and once for the body of your report.
BUT, it won't do any good to place the field in the body several times to get several listings of a field, such as census, which a person may have multiple facts. It will only lists the first one multiple times. (the same for spouse, only one listed)