Dig a round hole 12 inches deep and 12 inches wide for the post location. Measure carefully, as removing the base once the post is in is difficult.
Mix the 80 lb. bag of concrete with water as the bag instructions direct. Pour the concrete into the hole and level it evenly with the surface.
Place the post holder and extensions into the concrete while it is still wet. The extensions go deep into the concrete, ensuring that the post holder will not uplift or shift.
Set the post into the holder after the concrete has dried and set. This normally takes several days.
Hammer or screw the post to the post holder to keep it in place. Test the stability of the post by pushing and pulling on it. There should be little or no movement of the post. The post is now ready to support a frame and carport roof.