RS-485 Configurations help

Hello, I have came across this RS-485 tutorial, but I am farily new to this and I need some clarifications.

I am currently running the latest Debian image on my beaglebone black

Linux beaglebone 3.8.13-bone70 #1 SMP Fri Jan 23 02:15:42 UTC 2015 armv7l GNU/Linux

On the logic supply website,

Let’s dive into the Kernel a bit to to see how RS-485 works in Linux; the standard steps to put a UART into RS-485 mode are:

  1. Open the special tty file
  2. Create a serial_rs485 struct and set the desired configuration values
  3. Pass the configured struct to Kernel driver by using ioctl on the open serial port file descripto

Website: http://inspire.logicsupply.com/2014/09/beaglebone-rs-485-communication.html

I am kinda lost on where to find this special tty file (is it from some .dts file?), and where to put the serial_rs485 struct. Can someone guide me through this process on how to do this?

Thanks.