A Stub is a routine that doesn't actually do anything other than declare itself and the parameters it accepts and returns something that is usually the values expected in one of the 'happy scenarios' for the caller. Stubs are used commonly as placeholders for implementation of a known interface, where the interface is finalized/known but the implementation is not yet known/finalized. The stub contains just enough code to allow it to be compiled and linked with the rest of the program.
Help is readily available for resolving compiler errors. Magdiel or Jonathan are available Sunday-Thursday evenings 7-10:00. They both have completed CPTR 314 and are familiar with C++. If they cannot help you or you need help with compiler errors at other times, send me the offending source code and I'll help you resolve the problem.