Tap the dial once per leg of Sa'i between the hills of Safa and Marwah — it tells you the direction of your current leg automatically.
Odd legs run Safa → Marwah, even legs run Marwah → Safa. Sa'i always starts at Safa and ends at Marwah on the 7th leg. Men jog briskly between the two green markers along the way.