The lower left of the screen is your Project window Browser, which is like a file cabinet for your project within which you put your media files - audio, video, still pictures, and sequences/timelines.
You can create folders - which are called bins - within each project in the Browser to organize your media files.
To see what's in a folder, just click on the tiny triangle to the left of its name.
The files can be individual files, such as individual clips, or sequences, which are the sequences of clips you will create in the Final Cut Pro Timeline.
You can get more details on the files in your Browser by hovering your mouse over the project window and pressing the "~" key. Your whole screen will become the project window. Press the "~" key again to stop panicking. The new columns will tell you which files are video, which are audio, which are both video and audio, how many tracks of audio there are, the duration of each clip, etc.
Just above the Browser is the Source Preview window, where you can display and play individual video clips you drag from the Browser.
If you double click on a video clip in the Project Browser, it will be displayed in the Viewer.
Just below the clip in the Viewer is the playhead, a small blue triangle-ish thing in the wide horizontal box (with tick marks) that you can click on and drag to the left or right to move or scrub through the clip.
Beneath the playhead is a Play/Stop button you can use to play or move through a clip.
You also can play a clip in the Viewer by pressing the spacebar (while the Source Preview window is active) on your computer. To stop playing the clip, just press the spacebar again.
If you drag a video clip that also has two audio tracks from the Viewer into the Timeline, it will be displayed in the Timeline as a single light blue horizontal video track, with two separate darker blue horizontal audio tracks underneath.
If you then drag another clip down from the viewer you could drop it onto the timeline to the right of the first clip, so it would play after that first clip in your sequence.
You can continue this process to create a sequence of clips along your Timeline.
Just above the top video track in the Timeline is the playhead, a tiny blue triangle-ish object you can click on and drag to the left or right to move or "scrub" through your sequence of clips.
To see the entire sequence of clips, on your keyboard press " \ ". Premiere will then zoom out to reveal all the clips in the timeline.