The parts of the window

Menu bar

File, Edit, Media, Export, Tools, View, Help. Everything is reachable from here, and a greyed out item explains itself when you hover it. "No edits to undo" is more use than a dead button.

Toolbar

Carries the three working views as buttons: Clip, Combine and Convert. They are disabled until you have loaded something.

Media Bin

On the left. Open Media, or Ctrl+O, brings files in. The bin shows what a file is before you commit to it: duration, format, dimensions, codec and rate.

Selecting a file is what the rest of the window acts on. Most of the "nothing happens" moments come from nothing being selected.

Preview

In the centre. In Video mode it plays the picture. In Audio mode it draws the waveform with draggable selection edges, which is the better way to find a cut by eye.

A file in a codec the preview cannot decode still converts and exports correctly. It just does not play in the window. The bin shows the codec, which is where to look when a file behaves oddly in the preview but comes out fine.

Timeline

Below the preview. In Clip view it carries the in and out handles. In Combine view it shows the ordered list of pieces. In the Composite builder it shows the visual segments.

Properties

The settings for whatever you are doing: export format, quality, rate control, dimensions. It changes with the view.

It can be docked left, right or along the bottom from View → Dock Properties, and the choice is remembered in your data folder.

Status bar

Along the bottom, and worth reading. It reports what just happened in plain words, and it is usually where the answer is when something did not do what you expected.

Job queue

Export → Show Job Queue, or the Batch view. Work runs in the background and reports here with progress and a Cancel button on each row. A failure shows its error on the row rather than in a dialog you have already dismissed.

Rearranging

The View menu toggles Media Bin, Preview, Timeline and Properties on and off, so you can give the whole window to one thing while you work.

Panel dividers can be dragged, and they can also be reached with Tab. Arrow keys resize, Shift moves faster, Home and End set the limits.

View → Restore Default Layout puts everything back. Use it the moment the window stops making sense rather than trying to drag your way out.