Order by event date from Custom Press custom field

I have set up a custom events area: http://www.johnstonnorthamerica.com/jna_events/ and would like to query the posts to order by the event date, and then to drop off the archive once the date has past.

I have done this before, but only when I created my own custom post types in the functions.php file.

I know how to add the query to the archive page, but how can I find the meta key for the event date field? Would it be the same as the "field ID"?

Thanks for your help!