Installing Arduino Yun 1.1 shield

Hello. I have a problem to change boards.txt file to add there lines for Arduino Yun. Windows writes me "Access denied". I'm using Windows 8.1 Professional. I've already tried to change file attributes and "Safety" tab settings. Nothing helped me.

"Arduino Yun 1.1 shield" ?

The product url?

sonnyyu: "Arduino Yun 1.1 shield" ?

The product url?

http://wiki.dragino.com/index.php?title=Yun_Shield

Setup Dragino and Arduino IDE