I'm afraid this is a silly question, but here goes.
I have downloaded the GeoLocation plugin and added it my main page navigation. I have added this line to show.php
<?php echo geolocation_google_map_for_item($item,$width='200',$height='200'); ?>
But what data is required in the item record in order to locate it on a map. Right now the item record indicates: "This item has no location info associated with it."