vc#中pictureBox控件怎么加滚动条?

加载一幅图后,当看不完全的时候,怎么加滚动条?
                            rivate void button1_Click(object sender, System.EventArgs e)
{
openFileDialogPic.ShowDialog();
Bitmap bmp;
bmp = new Bitmap(openFileDialogPic.FileName);
pictureBoxLook.Image = bmp;
}