The Zozo stuff can be confusing, but I believe you're looking to go into the building with the "Cafe" sign on it, if I'm not utterly mistaken, which I may be. It's the building in the lower left region of the city.

Go in there, go up the stairs, and simply jump between as many windows as possible. I think that in one room there's a tricky looking wall, something like this:



Please forgive the crude picture.


Anyway, those two black lines are actually "hidden" hallways. You can walk through those to get to another part of the room. You'll know the room when you find it.

If you end up meeting a guy called "Dadaluma" who asks how he can be of service, and then tells you how he hates fighting you're almost there.

By the way, if you're in World of Balance, you're not in Mt. Zozo. That's totally different than the city of Zozo, which is where you are. Mt. Zozo is accessed through the door in Zozo that is rusted shut, much later in the game.