Map help!

Does anyone know how to create a map of a real city? I’ve tried and tried everything I’ve read online over and over and I don’t think I’m getting it. Can someone please help walk me through how create a map to use in the overlay mod? I know where the files go and everything I just can’t get the street view onto the map editor no matter what I do. Every time I make the map one heights map, I can’t get the street view.