Lay the door and frame assembly on a canvas tarp spread on a flat section of ground.
Apply a waterproof membrane to the bottom of the rough door opening.
Apply silicon sealant to the bottom of the door frame. Fit the frame into the opening.
Measure in two inches from the ends of the sill and make pencil marks at these points. Drill two holes at these marks. Secure the door with 3-inch wood screws. Apply silicon sealant to the ends of the sill and insert the end caps which are provided with the door.
Open the door in the frame and fit the frame into the opening. Check the door with a level and insert shims if needed.
Drill pilot holes in the frame for the wood screws then insert the screws. Make sure you apply silicon sealant to the bottom of the head before securing the screws.
Apply silicon sealant to gaps between the door frame and the opening. If the gap is wide, then use expanding foam. Trim all excess to create a smooth, flat surface for the foam. Install casings, trim and molding to finish the look of the door.