Itinerary's when opened initially will show a list of all bookings or schedule items that have been attached to your trip. There are a number of types of bookings which are represented by different symbols for flights hotels , transport etc.
You will always be landed in your itinerary with items for today and the future shown and those in the past hidden for convenience. There are two symbols like this that allow you to see and hide the past itinerary items.
By touching any item you open it and expose the itinerary assistance features. In the flight example below you can see three options.
Manage Booking will place your airline booking reference on your clipboard and take you directly to the airline website allowing you to paste that booking reference for check-in or booking management.
You can add this item to your calendar.
If you click "Directions" you will be taken to Google maps with directions requested and the airport location already entered as your destination.
There is a printer symbol at the bottom left of the screen which allows you to create a pdf version of your itinerary for sharing with others who are not on the trip.