C Sharp :: Saving Picturebox Image With Graphics In It

What i'm trying to do is load an image from my database create some graphics to it. probably just some lines and marks and save it back to my database. here's so far what I got.
 
for creating graphics:  
 } private void pictureBox3_MouseDown(object sender, MouseEventArgs e) {
            draw = true;
        } private void pictureBox3_MouseMove(object sender, MouseEventArgs e)  {
            if (draw)  {
                Graphics g = Graphics.FromImage(pictureBox3.Image);
 
[Code] ....

but the saving part doesnt work :( I think it only saves the image loaded to the picturebox but not the graphics created to it. how to merge it? i've tried to google it and found some sort of same cases but fails to make it work, something like converting it to bitmap.