To set up your Event Countdown page (or section), you need to first create a new page. You can also choose to add a new Grimlock section to a widget area (granted the Grimlock plugin is correctly activated).
After this, simply insert the following into the content area when editing the page/section:
[tribe_event_countdown slug="late-night-party" show_seconds="yes" complete="Sorry, but this event is over!"]
We hope this will be helpful. ?