Draw on picturebox image using c sharp .net

private void loadImageToolStripMenuItem_Click(object sender, EventArgs e)
       {
           try
           {
               OpenFileDialog open = new OpenFileDialog();
               open.Filter = "Image Files(*.jpg; *.jpeg; *.gif; *.bmp)|*.jpg; *.jpeg; *.gif; *.bmp";
               if (open.ShowDialog() == DialogResult.OK)
               {
                   pictureBox1.Image = new Bitmap(open.FileName);
                   trackBar1.Value = pictureBox1.Height;
                   trackBar2.Value = pictureBox1.Height;
               }
           }
           catch (ApplicationException ex)
           {
               MessageBox.Show(ex.Message.ToString());
           }
           trackBar1.Enabled = true;
           trackBar2.Enabled = true;
           pictureBox1.Enabled = true;
           lineToolStripMenuItem.Enabled = false;
       }
//code for creating drawing
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            Graphics g = null;
            g = Graphics.FromImage(pictureBox1.Image);
            g = pictureBox1.CreateGraphics();
            g.DrawLine(Pens.Red, 0, Convert.ToInt32(trackBar1.Maximum) - trackBar1.Value, Convert.ToInt32(pictureBox1.Width), Convert.ToInt32(trackBar1.Maximum) - trackBar1.Value);
            g.DrawLine(Pens.Blue, 0, Convert.ToInt32(trackBar2.Maximum) - trackBar2.Value, Convert.ToInt32(pictureBox1.Width), Convert.ToInt32(trackBar2.Maximum) - trackBar2.Value);
            g.Dispose();
            mouseMovePt = e.Location;
        }
// code for saving image
private void saveImageToolStripMenuItem_Click_1(object sender, EventArgs e)
        {
            SaveFileDialog savefile = new SaveFileDialog();
            savefile.DefaultExt = "jpeg";
            savefile.Filter = "All files*.*|*.*";
            if (savefile.ShowDialog() == DialogResult.OK)
            {
                int width = pictureBox1.Width;
                int height = pictureBox1.Height;
                Bitmap bitmap = new Bitmap(width, height);
                Rectangle rc = new Rectangle(0, 0, width, height);
                pictureBox1.DrawToBitmap(bitmap, rc);
                bitmap.Save(savefile.FileName, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
        }