There is no longer a separate shortcut to start Navigation (although existing links on your home screen apparently will not be removed). The shortcut is now just called Maps. Before there never was a separate Navigation app, just a Navigation shortcut.
I presume that you never updated your prior Maps app to version 7. It generally sucks compared to the older version, and has quite the learning curve. But to get started, start Maps. Assuming you're looking at a map screen, there will be a search box at the top, and at the right of that there will be a curved arrow icon. Hit that and it will bring up the navigation functions.
There will be a lot to learn. One thing important is to get a wide area view that shows traffic, you need to hit the the bottom right of the screen (three bar icon) and hit route preview. (There's also a tap, hit, slide down short cut, but it's not easier than just going through the menu.) The route line will be blue rather than green, but if there is traffic it will show a different color.