private void button_Click(object sender, EventArgs e)
{
string opcion;
openFileDialog1.Filter = "Bitmap files (*.bmp)|*.bmp|Gif files (*.gif)|*.gif|JGP files (*.jpg)|*.jpg|All (*.*)|*.* |PNG (*.png)|*.png ";
openFileDialog1.FilterIndex = 3;
openFileDialog1.FileName = "Seleccione una imagen";
openFileDialog1.Title = "Escoja una imagen";
if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
opcion = openFileDialog1.FileName;
BackgroundImage = Image.FromFile(opcion);
BackgroundImageLayout = ImageLayout.Stretch;
}
}