I think that there are two holes next to the sunvisor posts that you insert the Torx tool that was supplied with the car. Find the screw head and ...well, you know. Then the two right behind and above the seats. That is for an 84 top. Not certain about an 88 but I think it is relativley the same.
Targa Top is held in place with four bolts. Two in the rear and two at the bottom side of the front(swing visors out of the way)You can visibly see the rear bolts. The fronts are recessed. You should have received a ratchet for the bolt removal.