To get the most out of Catch2, start with the tutorial. Once you're up and running consider the following reference material.
Writing tests: Assertion macros Matchers Logging macros Test cases and sections Test fixtures Reporters * Event Listeners
Fine tuning: Supplying your own main() Compile-time configuration * String Conversions
Running: Command line CI and Build system integration
FAQ: Why are my tests slow to compile? Known limitations
Other: Why Catch? Open Source Projects using Catch Contributing Release Notes