If by three piece, do you mean it is canvas? w/ end cutains and a top? If so, them\n install the end curtains first by threading the rope through the gromets and around the front bow and then repeat for the rear bow but don't tie off the rear rope or you won't be able to get out of the truck.Roll the top over each bow starting from the front and even up the sides so they are even, tighten the end rope and tie off the side ropes. should take no more than a half hour. Unless you are referring to something else. then disregard my comments