Hi Jill,
It isn't possible to pick up the map from the locker. The Gravity Drop area can be tricky to locate. Did you manage to find your way inside the gate of that area? If you can get to the path where the ferris wheel is directly to your right, move forward and then right, and you'll see a gate - head for that.
Once inside, there are two arrows which lead off in slightly different directions, so move your cursor around for both of them. Try both and see where they lead.
Another tip: If you're standing at Tunnel of Terror, face away from the entrance.
Pan left and see a walled area to your left. That is Gravity Drop.
