There are a large number of tutorial posts related to working with MSG in the Studio Artist Effects Blog under the MSG tag. The Studio Artist Tips Blog also has a number of beginning MSG tutorials.
The cool thing about MSG is that you can work with directed evolution of MSG presets in the Evolution Editor to modify MSG presets as well as build your own from scratch. Without necessarily having to understand the technical details of advanced MSG Editing. High Level MSG Editing commands are also available in the integrated help browser. The links below are some effects blog articles to help get you started.
Here are some posts related to working with the Evolution Editor:
Directed Evolution of MSG Presets
Swap Evolving New MSG Presets
Evolving New MSG Preset with the Inspire Button
Using Add Mutation to Evolve New MSG Presets
Working with Inspire Evolution to BuildMSG Effects from Scratch
Working with Swap Evolution and a Fixed MSG Routing Configuration
Using Swap Evolution to Create a Variety of Different Procedural Effects
Evolving Self-Animating MSG Presets
There are a large number of active link help commands to edit MSG Preset available in the integrated Help Browser:
MSG Help Commands
Working with the MSG Configuration Help Commands
Using Meta-Edits to Build Complexity into a Simple MSG Effect
Color Gradient Meta Edit Commands