CppUnit comes with html-based documentation, generated from the source code by Doxygen (see DoxygenProgram). You can view the latest version's documents online.
Another source of information and assistance are the Discussion Forums. The topics are Help and an Discussion Forums: Open Discussion
Wiki Docs
Some important wiki docs are:
BuildingCppUnit1 (platform-specific build instructions contributed by users)
FrequentlyAskedQuestions - Frequently Asked Quesions (answers always needed!)
Web Docs
User documentation for CppUnit:
Tips on setting up CppUnit with VC++ 6 Images are in German, but helpful to non-German speakers anyway.
Simplified Chinese Document on CppUnit Source Code Analysis