You are a long way from where you think you are.
You are declaring and using the Map in he main() method. Local variables are inaccessible to "other classes", although they may be passed to methods/constructors of other classes (and final local variable are accessible to anonymous classes).
What does all that mean to you?
- make the map a private field of a CityList
- provide a getter for the map
- have code in another class create an instance of CityList and access the map via its getter to populate it
- have still other code test it from a main somewhere