Hi Anne-Marie!
Tell us: how will your program be run?

Is it on a websever with pages delivered to a webbrowser?
- if so, JavaScript is fine but a CGI script on the server would be better because JavScript might be deactivated on the client browser. You'll have to understand the concept of CGI first to do that.

Is it an application running on its own and you gave the JavaScript example just to make clear what you want to do because you know JavaScript?
- if so, you might want to look at perl's modules for TCL/TK in order to get popups.

HTH