Go to FH. That's the town in the middle of the ocean where theres a long bridge across. Just drive up to it with the Garden and can access it by going through the door at the end of the second floor corridor (or first floor, the one with the your classroom). When you get to the big bowl type area, walk right before entering it and keep going until you get to where you fought the tank. Head up the steps and it's pretty straightforward from there.