Directly below the menus are the main transport controls, including the fast forward and rewind buttons; the jog/shuttle controls; the play loop, play range/selection and play from playhead buttons; the stop button and the record enable button (the big red button). Play around with these if you aren't sure what any of them do.
Next to the transport controls are the main clocks. Clocks in Ardour can display time in four formats, which can be accessed by right-clicking on the clock face and selecting a mode. As you become more experienced with audio, you will learn the advantages and disadvantages of each format. For now, leave them on the defaults. We'll go over what some of those do later on. You can float the main toolbar into its own window by clicking on the small chevron in the top right corner of the window.
New in Ardour 2.0 are the edit mode selector, the cursor selection buttons and other controls below the transport controls. We'll go over some of these in a later section. To the right of the cursor selection buttons is the edit clock, which shows you the position of the edit cursor.
Below the controls are the rulers. These thin horizontal bars display the timelines which help you see when exactly a region or sound starts or stops. Also displayed with the rulers are the meter and tempo markers, the location markers, the range markers and the loop/punch ranges.
The tempo and meter markers help you define the speed and structure of the session's rhythms. The location markers are how you generate index marks for a CD, as well as place markers at important moments in your session. The range markers allow you to bounce or export any section of the session to an audio file. The loop/punch ranges are last; they allow you to either loop a certain section of the session or define punch ranges.