The easiest way to add a field to the list of query output fields is to check the checkbox at the left of the field name in the Query Building Area. To include all the fields of the object you should click the checkbox at the left of the asterisk item of the object.
Another way is to select a field name from the drop-down list of the Expression column in the Columns Pane. And the most common way is to write any valid expression in the Expression column in the Columns Pane.
To remove a field from the list of query output fields you should uncheck the checkbox at the left of the field name in the Query Building Area or you may remove it by unchecking the Output column checkbox.
Such operations as removing lines from the Columns Pane or re-ordering output fields are available by right clicking on the leftmost gray column via the drop-down menu.

The output field's aliases may be defined in the Alias column of the Columns Pane.
