You have to go into Application Properties" and unlock the application so you can edit it.
you can unlock it and customite it
It sounds like you may have provisioned a Packaged Apps Only workspace. You would need a Full Development workspace in order to customise your application. Please note that it is against company policy for Oracle employees to use our external hosted instance, apex.oracle.com. You should only be using our internal hosted instance, apex.oraclecorp.com.