Google Map feature can be enabled through "Admin home > Features > Google Map".
It can be initially set up for the whole Tiki through "Admin home > Google Maps" (tiki-admin.php?page=gmap).
First time, it will recognize that you don't have any Google Map key for your specific web site domain (required), and it will suggest you to request one at:
http://www.google.com/apis/maps/signup.html
One you complete the process in the Google site side, yuo can come copy the generated key to the correspongfing field in tiki-admin.php?page=gmap. Once done, you will be able to see your map below, like this: