Every event that you create is by default scheduled to the time zone of the calendar in which you create the event.
To create an event in a time zone other than the calendar default time zone, perform the following steps:
Create the event by following the steps described in
How Do I Create an Event?
Tap the Time Zone button from the New Event tab toolbar.
The Time Zone Settings pop up window appears with a list of all the time zones.
Select the time zone from the drop-down list.
Tap Set to set the time zone for the event.