Set the published inbound course and turn direction, then dial your arrival heading. The tool shades the three entry sectors, draws the 70° line, names your entry (Canadian: parallel / offset / direct), and flies it into the hold.
Reading it: the fix is at centre; the racetrack is on the holding (turn-direction) side. Your aircraft sits at the bearing you are arriving from and points at the fix. Whichever coloured sector it lands in is your entry. The 70° line splits the offset wedge from the parallel sector. Illustrative geometry — verify against the AIM / your ops before instruction.