There is no special thing that you need to do to get to book an executive room in Dubai. All you need to do is get in touch with the Free Zone Authority and they would handle the rest. You would get your booking as you need it.
What is the cost of getting an executive room?
The cost varies from free zone to free zone. Usually, executive room is one of the most expensive options available. So, you need to check with the free zone authority for the exact details on price.