To add a Comment Marker, open a clip by double-clicking on it, position the play head at the beginning of the section you'd like to add the marker to, and either click on the Comment button in the Marker Type panel or press the number 2 at the top of your keyboard.
Type in a comment and then drag the handle at the end of the comment to specify its duration.
You can modify a comment by clicking and dragging the handles or by selecting it and viewing options in the Marker Inspector panel.
