How do you edit the Plist?

Hello everybody,

I have just completed my first hackintosh setup using this exact build : http://snazzylabs.com/article/skylake-mac-mini-hackintosh/ (All the way down to the case).

I'm trying to follow a guide on how to enable multiple displays on this system. The guide can be found here.

How do I edit the Plist? I think once I can open the Plist I'll be able to figure it out but until then I'm kind of stuck. Any help would be appreciated.

Thanks in advanced