Passing local image to facebook wall

Question

I'm working on image sharing using facebook library to facebook wall and here is my code

/**
 * Function to post to facebook wall
 * */
public void postToWall() {
    // post on user's wall.
    Bundle params = new Bundle();
    params.putString("name", "name");
    params.putString("caption", "caption");
    params.putString("Discription", "Discription");
    params.putString("link", "https://play.google.com");
    params.putString("picture", "http://s3.buysellads.com/1266299/271750-1433251436.jpg");
    facebook.dialog(this, "feed", params, new DialogListener() {

        @Override
        public void onFacebookError(FacebookError e) {
        }

        @Override
        public void onError(DialogError e) {
        }

        @Override
        public void onComplete(Bundle values) {
        }

        @Override
        public void onCancel() {
        }
    });

}

here i'm posting picture using "http://s3.buysellads.com/1266299/271750-1433251436.jpg" but i need to post the image either from drawable folder or from sdcard. please help me Thank you...