Locate ceiling joists using the stud finder. Mark these locations with the pencil; these points will be where mounting screws are inserted to support the beam.
Cut as many 1-by-4 planks as necessary to span the desired ceiling length. Screw these to the ceiling joists with the drill, Phillips bit and wood screws, applied every 6 inches.
Place three 1-by-4 planks together to form a three-sided box. Drill pilot holes to accommodate screws, inserted to attach the three pieces.
Place the three-sided box over the plank attached to the ceiling. While holding the box in place (an assistant is useful for this), drill pilot holes for screws inserted every 6 inches. Drill in the screws using the drill and Phillips bit.
Apply wood filler over the screw heads. Sand down the filler until it's flush with wood surface. Paint or stain the three-sided box to give the appearance desired. Use a rocker dipped in paint or stain to give a faux "grain" appearance if desired.
Repeat all steps to create as many faux beams as desired.