If you want to create a new DDS printer file and work with it in Report Designer, you first create the member in your preferred way. To do this, you can for example select the workbench File menu and then New > i Source Member, or right-click the source file where you want to add the member and select New > Member.
This will open the New Member dialog. Enter the required information, the name and type of the member, and press Finish to create it.
What happens next, depends on the view from where you started the action. If you started it from the Remote Systems view, the Remote Systems LPEX Editor opens. Close it and open the member with Report Designer by right-clicking on it and selecting Open With > Report Designer. If you started the action from the i Project Navigator view, the editor that opens depends on the preference setting for the member type. The default here is also the Remote Systems LPEX Editor, but you can change it to Report Designer. See Making Report Designer the default editor for DDS printer files on how to do that.
When the new member is open in Report Designer, it is empty, as you would expect. There are no records yet and the Outline view only contains the file entry. Now, you can add records and fields, and define new reports the same way as you would when modifying an existing file.