Main application navigation is done through a dropdown menu in top action bar:
Action bar is the one at the top of the screen (or bottom in maps). At the right of the bar you can see the actions:
It's very probable that your phone hasn't enough space to show all the actions. In this case you have to press on the three vertical points or your phone MENU button to get the actions that doesn't fit (it depends on device and Android version).
Please remember that while you read the help. Because it's possible you don't see the actions like in the screenshots.
Now that you know how to navigate and find actions I recommend you to go to the Fast Introduction.