Welcome to the bleeding edge with the V3!
But, the principle is basically the same as using RPi with any 3D printer. But first, get your printer assembled, tested, calibrated and printing nicely before going down the RPi path. It adds an extra layer of complexity for inexperienced users.
You should also familiarize yourself with the RPi and install OctoPrint or AstroPrint. And, you should get the RPi connected to your WIFI network. Do all of this before you connect it to your printer and you'll be off to a much better start.
AstroPrint info:
https://www.astroprint.com/downloads - get the image and learn how to install and configure
OctoPrint info:
http://octoprint.org - get the image and learn how to install and configure
As far as connecting the RPi, it looks something like this:
1) mount RPi near the RAMBo
2) power RPi with 5V. You can either use supply from RAMBo or I plan to use a 5V wallwart supply. There are a couple of recent threads on how to power from RAMBo
3) make sure you've installed OctoPrint or AstroPrint and are connected to your WIFI network
4) hook USB from RAMBo to RPi - this is the "magic" connection
5) launch a web browser and connect to your RPi
6) configure OctoPrint/AstroPrint so it can talk to your printer, I recall that there is some configuration you need to do (port, serial speed, ..)
7) print!
But seriously, since you are new to all this, get the printer working and learn to use a control app like MatterControl or Repetier Host first.