I have written PKCS#11 wrapper for .NET called Pkcs11Interop which comes with unit tests covering all functions provided by PKCS#11 API. You can take a look at its LowLevelAPI tests which can be easily mapped to ANSI C.

You should also consider reading at least "Chapter 2 - Scope", "Chapter 6 - General overview" and "Chapter 10 - Objects" of PKCS#11 standard.