If you'd like to install an App on the Fire TV, the easiest way to do this is using the Fire TV search feature.
Find App using Voice Search:
On the remote, press and hold the voice/microphone button
While holding the button, say the name of the app you want to search for
OR, find App using remote:
Using the Fire TV remote, press the Home button.
From there, scroll LEFT to the search icon.
Press down and start selecting the letters of the App you want
Once you see the app name below, move down to it and select the app
Install the App
Verify the app you want is highlighted and Select it
Select "Get"
Once installed, you can select "Open" to launch the app
Finding your App
Once installed, the app may show up in your recent row on the home screen, but if you want to move the app so you see it in Your Apps & Channels without having to scroll over to get it, follow these instructions:
From the home screen, press down three times to get to the Your Apps and Channels row (not the Recent Row)
Press LEFT and select "See All" to see all of Your Apps & Channels
Find the App you want to make more readily available (if it's the one you just installed, it will be all the way down at the bottom right corner)
With the app highlighted, press the Options button (three horizontal lines) on the remote
Select Move
Press up/down/right/left to position the app where you want
Press Select to place app in that position
Done!
Note: The first row/5 apps are the ones you see on the home screen without scrolling, but you can access ALL of your apps from the home screen by continuing to scroll right in that row.