Understanding The FCPx Video Editor Magnetic Timeline
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 |"