When working in Premiere Pro, your project timeline is referred to as a Sequence.
Drag your first video over and drop it on your timeline. This will create your 1st sequence.
Once created, you can drag and drop video files, audio files, and photos into the sequence.
The top half of the sequence timeline is video file layers labeled as V1, V2, etc.
The bottom half is audio file layers labeled as A1, A2, etc.
You can add more video and audio tracks by right-clicking in the space right above or below the video/audio tracks
There are some helpful buttons to use in a sequence’s layer sidebar. The most used are:
Turns the visibility of the layer on and off in the project display window.
Locks a layer from being editable.
Mutes an audio layer from being heard during playback.
Dragging the bar will move your timeline left or right. (Wheel of the mouse)
To zoom in or out of your timeline, make the bar shorter or longer. (ALT + Wheel of the mouse)
Projects can have multiple sequences.
To start a new sequence, click File > New > Sequence.
The new sequence dialog box that lets you pick your sequence settings and name your sequence.
It is not overly important to pick your sequence settings because when you drag your first video clip over it will ask if you want to match your sequence to your clips settings. (which yes, you do!)