Measure and mark the wall where the faux beam will be installed.
Position a 2-by-2 board on the ceiling at the installation site. Angled corners can be cut using an angle finder and a miter saw. You need to attach the 2-by-2 to a ceiling joist; these can be found behind the drywall using a stud finder. Ensure that the 2-by-2 is flush and secure against the wall by attaching it using 3-inch wood screws.
Measure the faux wood beam. Use an angle finder and miter saw to cut it.
Attach the faux beam to the 2-by-2. Use the 3-inch screws to go through the beams and mostly through the 2-by-2.
Apply matching-colored wood putty over the screws. Give the putty approximately an hour to dry and then sand it until smooth.