How to Enable multiple upload

Hi Xamarin Forum,

Can someone help me about multiple uploading I have used James Montemagno's File uploading and image cropping but the docs is a little bit short to describe on how to make a multiple upload anyway here is my code that is currently using:

XAML

 <StackLayout>
            <Button Text="Pick image" Clicked="Select_Pic"/>
            <Image x:Name="imageView" Aspect="AspectFit" />
            <Controls:CustomEditor Placeholder="Write a Description.." x:Name="postContent" HeightRequest="100"/>
            <Button Text="UPLOAD" Clicked="Upload_File"/>
 </StackLayout>


Code Behind 

public partial class PostCreationPage : ContentPage
    {
        public PostCreationPage ()
        {
            InitializeComponent ();

        }
        private MediaFile _mediaFile;
        private string URL { get; set; }
        ImageSource ImageSrc;

        private async void Select_Pic(object sender, EventArgs e)
        {
            string[] fileTypes = null;

            if(Device.RuntimePlatform == Device.Android)
            {
                fileTypes = new string[] { "image/jpeg" };
            }

            if (Device.RuntimePlatform == Device.iOS)
            {
                fileTypes = new string[] { "public.image" };
            }

            await CrossMedia.Current.Initialize();

            if(!CrossMedia.Current.IsPickPhotoSupported)
            {
                await DisplayAlert("Error", "Image file type not support.", "OK");
                return;
            }
            else
            {
                var mediaOption = new PickMediaOptions()
                {
                    PhotoSize = PhotoSize.Medium
                };

                _mediaFile = await CrossMedia.Current.PickPhotoAsync();
                if (_mediaFile == null) return;

                imageView.Source = ImageSource.FromStream(() => _mediaFile.GetStream());
                var memoryStream = new MemoryStream();
                await _mediaFile.GetStream().CopyToAsync(memoryStream);
                byte[] imageAsByte = memoryStream.ToArray();

                await Navigation.PushModalAsync(new CropView(imageAsByte, Refresh));
            }
        }

        private void Refresh()
        {
            try
            {
                if (App.CroppedImage != null)
                {
                    var imageCrop = App.CroppedImage;
                    imageView.Source = ImageSource.FromStream(() => new MemoryStream(imageCrop));
                    var layout = new StackLayout();
                    var btn = new Button { Text = "Upload" };
                    CustomEditor CustomEditor = new Controls.CustomEditor { Placeholder = "Write a Post...", HeightRequest = 100, };



                }
            }
            catch (Exception ex)
            {

            }
        }

        private async void Upload_File(object sender, EventArgs e)
        {
            if (_mediaFile == null)
            {
                await DisplayAlert("Error", "There was an error occured when trying to get your image.", "OK");
                return;
            }
            else
            {
                UploadImage(_mediaFile.GetStream());
            }
        }

        private async void UploadImage(Stream stream)
        {
            string[] fileTypes = null;
            string filename = _mediaFile.Path;
            string userfirstname = App.FirstName;
            Pipeline databaseConnect = new Pipeline();
            var imageCrop = App.CroppedImage;
            BinaryReader br = new BinaryReader(stream);
            byte[] bytes = br.ReadBytes((Int32)stream.Length);
            var page = new LoadingPage();
            await stream.ReadAsync(bytes, 0, (int)stream.Length);

            try
            {

                await PopupNavigation.Instance.PushAsync(page);



                SqlCommand sqlInsert = new SqlCommand("INSERT INTO tablename(Post_Content, Photo, Uploader, Date_Uploaded) " +
                    "VALUES(@PostContent, @Photo, @Uploader, @DateUploaded)", databaseConnect.connectDB());
                sqlInsert.Parameters.AddWithValue("@PostContent", postContent.Text);
                sqlInsert.Parameters.AddWithValue("@Photo", imageCrop);
                sqlInsert.Parameters.AddWithValue("@Uploader", userfirstname);
                sqlInsert.Parameters.AddWithValue("@DateUploaded", DateTime.Now);
                int i = sqlInsert.ExecuteNonQuery();
                databaseConnect.connectDB().Close();

                if (_mediaFile == null)
                {
                    await DisplayAlert("Error", "There was an error when trying to get your image.", "OK");
                    return;
                }
                else
                {
                    await DisplayAlert("Success", "Uploaded to Database.", "OK");
                    await PopupNavigation.Instance.PopAsync();
                    await Navigation.PopAsync();
                }
            }
            catch(Exception ex)
            {

            }
        }
    }

So how can I insert multiple uploading in this code
TIA