byte[] fd;
OpenFileDialog o = new OpenFileDialog();
if (o.ShowDialog() != DialogResult.Cancel)
{
    filename = o.FileName;
 
    FileStream st = new FileStream(filename, FileMode.Open, FileAccess.Read);
 
    FileInfo fi = new FileInfo(filename);
    fd = new byte[fi.Length];
 
    st.Read(fd, 0, (int)fi.Length);
    st.Close();
}