how to store image in image control to server folder

hi  all,
i want to store image in server folder.
i know how to store image by using file upload control
but now i am not using file upload control
i will get image from external source like this one
<asp:Image ID="Image2" ImageUrl="http://www.programmingsimplified.com/images/c/hello-world- c.png" runat="server" /> now i want to store that image on server folder?
how can i do this?

Thanks,
Murali.