DesiShoots.com

This is an excellent resource here from Jonny Elwyn. Understanding the FCPx magnetic timeline.  for editing video.,

It starts from the basics and has a comprehensive writeup and video tutorials.

"Before we go much further it makes sense to translate a bit of FCPX terminology:

Library = Project | Event = Bin | Project = Sequence | Primary Storyline = Track 1 | Secondary Storyline = Other Tracks/Group of Clips | Roles = Tracks if you had stayed organised* | Compound Clips = Nested Group of Clips |"

_{and here's another one from Sound Snap blog.}

_{use the Primary storyline as an island of null gap and build your edit around it.}

https://blog.soundsnap.com/2018/03/09/understanding-final-cut-pro-x-magnetic-timeline/