FM synthesis can be confusing. To get the most out of the YM2612 and Micro-8's FM Sound Editor, I found this short introduction to FM Synthesis particularly interesting. It uses a 6-operators synth (DX7) but the principles can be transferred to the YM2612 4-operators.
Also, the following Playlist explains the basics of the Yamaha DX21 synthesizer which uses a chip quite similar to the YM2612. It has the same 4-operators 8 algorithms configuration.
www.youtube.com/playlist?list=PLf4riISxC...a-GAVV3up0AaKkCE19qS
