cgi command for images

[Anon]

If someone can help me with a cgi problem it will be very much appreciated.

I have this command (which works) and shows a certain image when the user does not upload one:

%default = (

'image1'=>'http://www.abc.com/images/none.gif');

What would the proper code or command be which will show the image when a user DOES upload one?

Much thanks,
Amy