Hi Marvin,
Creating events from the story form is a quicker way to create events, that's why it does not have the location field.
If you want to enter the location for the event, you can:
option 1. Create the event from story form first, then edit the event to enter the location.
option 2. Create the event using the 'full' form in the group, which should be available at the group's events page(
http://take.ms/0yLY0).