My level is Entrepreneur. I have access to all but four of the main por…

My level is Entrepreneur. I have access to all but four of the main ports and I only have access to one of the secret ones. I figure I'll get access to the other main ports once I become a master entrepreneur but I still don't know where most of the secret ones are. I got access to the Amazon early on and now I just really want to find the others. I keep clicking randomly on the pubs and I take every quest I'm given, is it random or do I need to do something specific to unlock them?