Problems with GUI in Visual Studio C# .Net

Hi friends!

I have some problems with GUI in C#.Net ,Can anybody solve these?

First ,How can I save the image from the PictureBox to the Harddrive…. Is it wrong  method or not for save the any image ? like as

//Save file

                        private void savebt_Click(object sender, System.EventArgs e)

                        {

                                    if (saveFileDialog1.ShowDialog() == DialogResult.OK)

                                    {

                                        filename =saveFileDialog1.FileName;

                                        Stream filestream =File.OpenWrite(filename);

                                    using(StreamWriter fwriter= new StreamWriter(filestream))

                                                { fwriter.Write(PictureBox.Image);}

                                    }

                        }

Second , I use the following codes for drawing into the pictureBox2   by Pen

private void pictureBox2_MouseDown(object sender, MouseEventArgs e)

        {  

                Pen p = new Pen(Color.Red, 5);

                g = pictureBox2.CreateGraphics();

            if (e.Button == MouseButtons.Left)

                { g.DrawEllipse(p, e.X, e.Y, 5, 7); }

        }

private void pictureBox2_MouseMove(object sender, MouseEventArgs e)

        {

               Pen p = new Pen(Color.Red, 5);

               g = pictureBox2.CreateGraphics();

            if (e.Button == MouseButtons.Left)

                { g.DrawEllipse(p, e.X, e.Y, 5, 7); }

        }

But there is a problem when I RUN the program and start the drawing if when I move the mouse fastly then such drawing break into small ellipse,I think you have understand

Third , I use follwing codes to draw the line into the pictureBox2 :

private void pictureBox2_MouseDown(object sender, MouseEventArgs e)

{  Pen p = new Pen(Color.Red, 5);

   g = pictureBox2.CreateGraphics();

   g.DrawEllipse(p, e.X, e.Y, 2, 2);

                    mx = e.X;

                    my = e.Y;

}

private void pictureBox2_MouseUp(object sender, MouseEventArgs e)

{

Pen p = new Pen(Color.Red, 5);

g = pictureBox2.CreateGraphics();

g.DrawLine(p, mx, my, e.X, e.Y);

}

But I confuse for that

 private void pictureBox2_MouseMove(object sender, MouseEventArgs e)

{

???????????????????????????????

}

I want when I move the mouse arrow onto the pictureBox2 ,then the line move with respect to the mouse and not draw untill UP the mouse button.

I am waiting for your kindly response

                                     Thanks