How to store an image as an image file in local system.

I have a image which is coming from server and i am able to load it on the page.
Now i need to store that image on local system how to do it....

Image image = new Image();
if (imagePath != string.Empty)
{
     Uri url = new Uri(imagePath);
     BitmapImage bitmapimage;
     bitmapimage = new BitmapImage(new Uri(imagePath, UriKind.Absolute));
     image.Source = bitmapimage;
}