How to download whole web page contents including images even from inside JavaScripts without using third party dll?

private void button1_Click(object sender, EventArgs e)
        {
            var client = new WebClient();
            string content = client.DownloadString("http://www.w3schools.com/");
            textBox1.Text = content;
        }

 
then saving the text of textbox1.text=content as html file.It's working and open as a web page, but problem is,if there are any images then not working,at the place of image there is small cross symbol.
 
So i want ur help, how can i download the images and other content also and link it to their place,to show it in proper format as webpage looks on net. (like we save any page and use it as a offline)
 
one thing i m not using website project, i m working through c# windows.
 
help