To begin, you'll need the Tiki tool, a square nut and screw, and the center fin. Start by having the screw, knot, and center fin ready. Place a square nut into the center of the fin box. Use the Tiki tool to slide the nut to the front of the box. Next, insert the center fin into the fin box with the pin side in first. Slide the fin to the back of the box so it is firmly in position. Then, slide the nut backwards into place and insert the screw. Finally, tighten the screw to secure the fin.