No, it wasn't completely simple to figure out exactly what was meant, but you're on the right track now. The reglar are in place and guide so the plank is planed flat. You will have to run it over the planer many times, as you notice. Consider running the plank from both ends alternately. The planer tends to take a bit more at the beginning and a bit less at the end. Otherwise, you risk getting a slope. You might also notice that it planes "finer" in one direction than the other, so you should finish in the finer direction "with the grain."
