Climb the ladder and go over to the roof vent.
Insert the pry bar underneath the shingles and pry them up. Pry up any roofing nails securing the shingles to the roof.
Pull off the shingles on the side and top of the roof vent.
Place the vent boot or flange over the top of the vent. Slide it down so that it is flush with the top of the roof. The top part of the boot should rest on the tar paper or roofing material and the bottom should rest on top of a row of shingles.
Attach the vent boot to the roof, using galvanized nails and the hammer. Alternatively, use galvanized screws with a power drill.
Replace the shingles around the vent pipe and secure them to the roof with roofing nails.
Apply a bead of caulk around the top of the vent boot where it meets the vent pipe to prevent water from leaking down the pipe.