The other guide offers some very helpful videos, but if you would prefer to explore and unlock this through natural gameplay - there is a map of the Seagate Park posted outside what seems like the management office (see screen cap for location) The door is locked, but notice the light-up park layout showing 4 red lights. Search those out in any order, puzzle through the challenges & the lights turn green when completed. This then allows access to the office to complete the backstory of the park. The challenges are standard Arkham fare, but again, Pingy's guide offers detailed videos if you get stumped.