Below is the part written in the set-up webpage
https://wiki.onion.io/Tutorials/Arduino-Dock/Initial-Setup#computer-setup_arduino-ide_modification-of-boards-txt

When I first try to edit and save boards.txt, it told me I have no access to it. Then I copied and edited in a different folder, erased the original one, and moved the edited to the Arduino program files. Then, I added Onion library zip file. When I compile, it gives me the error saying, it sees the error in boards.txt, saying '?#' ~~blah blah ~~

I don't know what to do.. I erased Arduino and every set up stuff and trying to do it again. It's so painful to make this work..

**Modification of boards.txt

The regular Arduino Uno has no way of communicating with your computer via WiFi, but the Omega provides the Arduino Dock with a means of wireless communication, so we'll have to let the Arduino software know! This requires a one line addition to the boards.txt file in your Arduino IDE installation.

Open the boards.txt file in any text editor. The following table outlines where the boards.txt file can be found:

Operating System Location of boards.txt
OS X /Applications/Arduino.app/Contents/Java/hardware/arduino/avr/boards.txt
Windows C:\Program Files (x86)\Arduino\hardware\arduino\avr\boards.txt
Once it's open, add the following line:

uno.upload.via_ssh=true
Doesn't matter where you add it, you can nestle it with the other uno. settings if you like.**

I followed step-by-step of this instruction, but it doesn't work when I change the boards.txt of Arduino program file.

Below is the part written in the set-up webpage
https://wiki.onion.io/Tutorials/Arduino-Dock/Initial-Setup#computer-setup_arduino-ide_modification-of-boards-txt

Warning if you have an Omega2(+) with Arduino Dock 2:
Arduino Dock Initial Setup tutorial is related to Omega (ie the previous version) and the first version of the Arduino Dock.
Use it carefully!

Onion Omega2 Documentation Flashing the Arduino Dock says

We did all of our testing using Version 1.8.0

So I downloaded arduino-1.8.0-linux32.tar.xz and installed onto the /opt directory of my Ubuntu 16.10 (32-bit) box and followed the above docu.

/opt/arduino-1.8.0
/opt/arduino-1.8.0/hardware/arduino/avr/boards.txt