My site has an overlay window on the home page that is displayed when the page is loading (see attachment). I want this window to be displayed to a specific area of Australia only, would that be possible and how would I do this?

I have also added a checkbox that will remember each visitor for next visits when they check it. I think I will have to use cookie sessions to make this work but I m not sure where to start. Any help will be greatly appreciated.

Thank you.