Uploading and retrieving image android studio Parse sever

I'm trying to pick multiple images from users gallery and upload (parse server) this images to parse object then retrieve it and set it in an image view

and also i need to pick one image from gallery and save to the users profile

what i have already tried:

//Before OnCreate 
String da = "13412412412412414124ASDASDASDASDAD";
////After OnCreate
 @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        final Uri imageUri = data.getData();
        final InputStream imageStream;
        try {
            imageStream = getContentResolver().openInputStream(imageUri);
            final Bitmap selectedImage = BitmapFactory.decodeStream(imageStream);
            String encodedImage = encodeImage(selectedImage);
            da=encodedImage;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
    private String encodeImage(Bitmap bm) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bm.compress(Bitmap.CompressFormat.PNG,100,baos);
        byte[] b = baos.toByteArray();
        String encImage = Base64.encodeToString(b, Base64.DEFAULT);
        return encImage;
    }
    private void ChooseImage() {
        Intent photoPickerIntent = new Intent(Intent.ACTION_PICK);
        photoPickerIntent.setType("image/*");
        startActivityForResult(photoPickerIntent, RESULT_LOAD_IMG);

    }
    private void CreateThing() {
        ParseObject thing = new ParseObject("Things");
        thing.put("Image",da);
        thing.saveInBackground(new SaveCallback() {
            @Override
            public void done(ParseException e) {
                if (e==null)
                    Toast.makeText(class.this, "Done", Toast.LENGTH_SHORT).show();
                else
                    Toast.makeText(class.this, e.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });
    }