Read and do these sections of the Exploring Logic Pro Manual.
Chapter 10: Automating Your Mix
Exploring Track Automation
Using Touch and Latch Modes
Creating and Editing Automation Nodes and Lines
Key Concepts
Chapter 9: Mixing the Project
Exploring the Mixer
Working with Channel Strip Groups
Adding Effects to Multiple Channel Strips
Creating a Submix
Routing Signals with a Multi-Output Instrument
Key Concepts
Work on your final project.