What does do in a C declaration

Question

As a C person, I'm attempting to comprehend some C++ code. 

The declaration of my function is as follows:

int foo(const string &myname) {
  cout << "called foo for: " << myname << endl;
  return 0;
}

How does the function signature differ from the equivalent C:

int foo(const char *myname)

Is there a difference between using string *myname vs string &myname? What is the difference between & in C++ and * in C to indicate pointers?

Similarly:

const string &GetMethodName() { ... }

Why are the and here? 

Is there a webpage that outlines the differences between how & is used in C and C++?