Tap the or buttons next to the date button to move the current date by one. Swipe the date button left to go forward one day and swipe right to go back one day.
To navigate to a day that is further away from the current date, tap the date button in the middle to pull up the calendar navigation view.
Swipe the session left or right to go to the next or previous session on the current day, respectively. Your current session indicator is the red dot at the bottom of the screen. The presence of other sessions on the current day is indicated by white dots.