First create a layout for Map Activity. The name of layout is activity_main.xml

 <fragment
                xmlns:android="http://schemas.android.com/apk/res/android"
                android:id="@+id/map"
                class="com.google.android.gms.maps.SupportMapFragment"
                android:layout&#95;width="match&#95;parent"
                android:layout&#95;height="match&#95;parent"/>

To add markerr in a specific lat long and move the map focus to this position.
For this use the following line of code:-

 // Get a handle to the Map Fragment
        GoogleMap map = ((SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map)).getMap();

        LatLng dehradun= new LatLng(30.316495, 78.032192);

        map.setMyLocationEnabled(true);
        map.moveCamera(CameraUpdateFactory.newLatLngZoom(dehradun, 13));

        map.addMarker(new MarkerOptions()
                .title("Dehradun")
                .snippet("Capital of Uttarakhand")
                .position(dehradun));

We can also change the type of Map. Following are the types of map:- 1) Normal 2) Hybrid 3) Terrain 4) None

To set the map type use following lines of code:-

GoogleMap map = ((SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map)).getMap();   

 map.moveCamera(CameraUpdateFactory.newLatLngZoom(
            new LatLng(30.316495, 78.032192), 2));

// Other supported types include: MAP_TYPE_NORMAL ,
    // MAP_TYPE_TERRAIN, MAP_TYPE_HYBRID and MAP_TYPE_NONE
    map.setMapType(GoogleMap.MAP_TYPE_SATELLITE);

To make path and routes on the map we use Polyline
Following line of code gives the example of how to make paths and routes on the map

 GoogleMap map = ((SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map)).getMap();

        map.moveCamera(CameraUpdateFactory.newLatLngZoom(
                new LatLng(30.316495, 78.032192), 2));

        // Polylines are useful for marking paths and routes on the map.
        map.addPolyline(new PolylineOptions().geodesic(true)
                .add(new LatLng(28.635308, 77.224960))  // New Delhi
                .add(new LatLng(-18.142, 178.431))  // Dehradun
                .add(new LatLng(22.572646, 88.363895))  // Kolkata
                .add(new LatLng(19.075984, 72.877656))  // Mumbai
        );