Snap a chalk line on the ceiling 5-1/2" away from the beginning wall running the width of the room. Line the first row of boards up with the line, not the wall. This is to ensure that you get a straight beginning line.
For any obstacles such as junction boxes, mark the board, take it down, use a jigsaw to cut the board, then re-install the cut board. All boards (after the first board) are nailed through the groove. This is called "blind nailing" All the nail heads are completely hidden when the tongue of the next board slides into the groove.
To fill the gap between the last board and the wall, take a series of measurements along the gap. Use the narrowest of the measurements to rip the last board. Use a flatbar to get the tongue and groove joints to fit tightly. Face-nail last strip into place.
Measure the room for the 1/4" round trim. Cut the trim down to size with a miter saw and nail it up with a pneumatic nailer. When butting two pieces of trim up to each other, cut opposite 45 degree angles on each end. This is called a scarf joint and gives a seamless transition.