Final Cut Pro > Easy Setup > DV NTSC Anamorphic.
Choose an easy setup in 23.98 an appropriate mode if you shot and are editing in 24p. If you don't know what that means, don't choose it.
This will only affect new projects started after the setup has been chosen. To change your current project, you'll need to alter the settings for your timeline to be Anamorphic, and set the anamorphic flag on all your captured clips.