Load File To Fileupload?

how to load a default file (example : noimage.gif) with fileupload if we not choose a file to upload?

here's my code:

if (FileUpload1.HasFile && FileUpload1.PostedFile == null)
{
}
else
{
binaryImage = new byte[FileUpload1.PostedFile.ContentLength];
FileUpload1.PostedFile.InputStream.Read(binaryImage, 0, binaryImage.Length);
if (ImageC.isImage(binaryImage))
{
System.Drawing.Image originalImage = new Bitmap(new MemoryStream(binaryImage));
System.Drawing.Image thumbnailImage = new Bitmap(originalImage.GetThumbnailImage(ImageC.thumbW, ImageC.thumbH, null, IntPtr.Zero));
MemoryStream thumbnailMS = new MemoryStream();
thumbnailImage.Save(thumbnailMS, System.Drawing.Imaging.ImageFormat.Jpeg);
binaryThumb = thumbnailMS.ToArray();
}
else
Response.Write("Format file is wrong.");
}