The scene tab is for extremely long scripts for which scrolling is inefficient to find a scene. A scene is scripting a background, characters, dialogue and actions, like this:
INT. BLACK - NIGHT
@CHARACTER enters from right to screen center
@CHARACTER is wave_extreme
CHARACTER
Hi, it's nice to meet you!
@CHARACTER exits left
That’s a whole scene. Doesn’t have to be fancy or complicated, just has to have a background and something happening on it.