Place the step stool at the back of the truck camper. If you're using an assistant, place another step stool at the side (does not matter which one) of the camper.
Slide the canoe onto the roof with the aid of your assistant. Use the stools to stand on to get the canoe up onto the tall surface. Position the canoe in the middle of the camper or next to any roof vents.
Position the Styrofoam canoe cradles at the front sides and rear sides of the canoe. Wedge them into the side of the canoe so there is no side to side movement possible from the canoe. Toss the ratchet straps over the canoe, one in front and one in the rear, so the straps hang to the side of the truck.
Attach the strap hooks to the underside of the truck and tighten with the ratchet on the straps. Do not over tighten, but get them tight enough so the canoe does not move.
Attach bungee cords to the front and rear of the canoe, either under the edge and combing of the canoe or through the bow and aft rope holes. Secure the bungees to a solid location on the truck.