Lay plastic sheeting or a drop cloth around the wood post to protect the concrete or patio flooring. Make sure to extend the protective barrier at least 2 feet in every direction around the post.
Place painter's tape around the top and bottom corners where the post meets the ceiling and floor. This will protect the finished ceiling and flooring material from the stain.
Apply a mild soap with water to remove any oil, dirt or dust from the post. Scrub the post with a wash cloth, rag or a bristle brush. Let the post dry completely before continuing.
Open the can of sealer using a flat head screwdriver or a paint can opener. Stir the sealer to ensure that it is mixed evenly.
Use a paint brush to apply sealer to the post. Stroke the paint brush in the direction of the wood grain. Apply the stain evenly to the entire post.
Remove the tape and plastic that was used to protect the floor once the stain has completely dried.