Having learned the issue tracking module, you may consider you have learned Redmine as most of its users work mainly with issues. Other modules are not as critical to know for a usual user and, as it has been mentioned, the whole Redmine interface is quite easy to understand. But as this book is not named "Redmine: The very basics" I assume you want to learn more to be able not just to use, but also to master Redmine. And also if you want, to manage with Redmine!

The next chapter is intended mostly for project managers and site owners as it describes the capabilities of Redmine as a project management and project hosting application. But it will also be interesting for usual users as it teaches how to navigate projects, find information, and shares best practices.