Measure the width of the ceiling, measuring in the direction perpendicular to the ceiling joist. Mark the measurement on a ceiling plank.
Cut it on your miter saw to length.
Hold the plank on the ceiling, along your starting wall, with the grooved side of the plank facing the wall. Leave 1/4 inch at the wall, for the wood to expand (the space will be covered later by ceiling trim).
Shoot two nails through the face of the plank at each point where it crosses a joist.
Measure and cut the next plank. Set it in place against the previous piece, locking the tongue & groove edges together.
Nail the second board up by shooting nails through the sides, at an upward angle, at each point where it crosses a joist, so the nails don't show on the face of the board.
Repeat for each board, building across the ceiling. Cut the final piece lengthwise on a tablesaw to make it fit in the last space with a 1/4 inch gap by the wall.
Nail through the face of the board as with the first board.
Measure ceiling trim for the edges of the ceiling. Secure it with your trim nailer.