The SDK comes with ready to build Location Acquisition API example, a perfect start for somebody that has yet to understand what "implement M*" means. A wiki article usually contains a code snippet that you are expected to integrate yourself, assuming that you have the knowledge.
Anyhow, an M class is a interface that needs to be implemented by a C class (e.g. your view class) so that external classes can call the methods implemented by C without having to know anything about its implementation, other that it implements M.
Now any object that knows how to use the M interface can manipulate C objects but only through that interface. So the code below
virtual void DoSomething() = 0;
// class implementing the interface
class C: public CBase, public M
// declaration, from M, definition is mandatory
// I'm doing something
can be used in the context:
void CAnyObject::UseTheMInterface(M& aMDerivedObject)
although CAnyObject is not aware of C's definition.
C *c = new (ELeave) C();
CAnyObject *anyObject = new (ELeave) CAnyObject();
So, check the declaration of MPositionReaderObserver and see which class in your project should provide the implementation for this interface in order to receive notifications when location info is available.