See where it says "Add [1] field(s) at", right below "Print view"?
Right after that are several choices: "At end of table", "At beginning of table", and "After [List of fields]". Select the one that you want to use, then click the "GO" button.
If you click the "GO" button without doing anything else, it'll start to add 1 field to the end of the table column list by default. After you click the button you'll have the opportunity to fill in the field name, column type, etc etc.
Really, that's all there is to it.