Use the tooltips. Briefly, they are:
New, Open, Save
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Save Still Frame
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Insert Before, Insert After
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Undo, Redo
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Cut, Copy, Paste Scene
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Split, Join
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Zoom
In Edit mode, click a scene to seek to its first frame.
In Trim mode, clicking a scene takes on different behaviour depending upon the current Trim editing mode. Briefly, in Overwrite mode, clicking a scene saves the changes to the current scene and choose a new a scene to trim. In Insert mode, clicking a scene sets the insertion point. See Trim for more information.
In Timeline, Export, or FX modes click a scene to select the region to thumbnail, export, or process, respectively.
Click, hold, and drag the triangle on the scrub bar to seek within the project. The vertical line breaks in the srub bar indicate scene positions.
The transport controls control playback and seeking. Hover the mouse over each button to get tooltip help description of each button.
Drag the shuttle to the left to play in reverse. Drag a little for slow play back, medium for normal, and a lot for fast. Drag the shuttle to the right to play forward. Release the shuttle to pause. The shuttle works in edit or capture mode.
Click the triangle to expand and collapse a properties panel. The panel displays extended metadata about the current clip and frame.
Choose a time format from the option menu. In edit mode, timecode displays running movie timecode. In capture, timecode display source camera timecode. See Time for more information.