C++ function question

This is a dumb question, brought to you by a dumb student. (yes there are both dumb questions and dumb people, I know from personal inexperience) I have a program written for my course that uses a simple function, no classes, structures, or Lists. I just reread the assignment and it said to put all function declarations in a header file and all function definitions in a separate source file. It does not say to use "member" functions as he states to use for classes, nor does there seem to be any purpose in using a class. I have been unable to break up these functions as requested, like I have done with classes. I have been unable to find any reference to it in either of the books I have or in on-line searches. Is there a way to do this?

//f.h
void someFunction();

//f.cpp
void someFunction()
{
do something;
}

//main.cpp
{
somefunction();
}