Creating Custom Overlay on the map

Okay, I tried to do things on my Own, and put this code to get the above effect:

public class MarkerOverlay extends Overlay {

    Geocoder geoCoder = null;

    public MarkerOverlay() {
        super();
    }


    @Override
    public boolean onTap(GeoPoint geoPoint, MapView mapView){
        selectedLatitude = geoPoint.getLatitudeE6(); 
        selectedLongitude = geoPoint.getLongitudeE6();
        return super.onTap(geoPoint,mapView);
    }

    @Override
    public void draw(Canvas canvas, MapView mapV, boolean shadow){

        if(shadow){
            Projection projection = mapV.getProjection();
            Point pt = new Point();
            projection.toPixels(globalGeoPoint,pt);

            GeoPoint newGeos = new GeoPoint(selectedLat+(100),selectedLong); // adjust your radius accordingly
            Point pt2 = new Point();
            projection.toPixels(newGeos,pt2);
            float circleRadius = Math.abs(pt2.y-pt.y);

            Paint circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);

            circlePaint.setColor(0x30000000);
            circlePaint.setStyle(Style.FILL_AND_STROKE);
            canvas.drawCircle((float)pt.x, (float)pt.y, circleRadius, circlePaint);

            circlePaint.setColor(0x99000000);
            circlePaint.setStyle(Style.STROKE);
            canvas.drawCircle((float)pt.x, (float)pt.y, circleRadius, circlePaint);

            Bitmap markerBitmap = BitmapFactory.decodeResource(getApplicationContext().getResources(),R.drawable.pin);
            canvas.drawBitmap(markerBitmap,pt.x,pt.y-markerBitmap.getHeight(),null);

            super.draw(canvas,mapV,shadow);
        }
    }
}

This let me have following effect:

The calculation used may not be what you want.
Its just for demonstration purposes.
Real range/distance calculation requires the use of bearing too and has some specific formula.

Let me know if you have any questions regarding this.