Select Finishing from the pop-up menu, and then select Half Fold (Print Outside), Half Fold (Print Inside), or Half Fold and Saddle Stitch from Fold/Saddle Stitch.
Set the other items as necessary.
If booklets or paper remain in the booklet tray, you will not be able to start bookbinding printing. Make sure there is nothing on the booklet tray.
Click Print.