Simply select the destination where you want to go from the displayed map on the main screen. Tap directly on the selected spot and a location marker will appear. At the bottom edge of the screen you will see some information about it, and a button labeled „Get directions“. Pressing that will show you the route which the app calculated to that destination, and the navigating will begin after you tap „Start“.
While browsing the map, especially as you zoom in more, you will notice small round icons with various symbols. These represent the locations of Places such as restaurants, tourist attractions, gas stations, shopping centers, etc. You can also select one of these as your destination by tapping on them, then pressing „Get directions“ to view the route.