Jailbreak iPhone iOS 6.1.6 using redsn0w on MacOS 10.6.8


I'm new here and not particular savvy when it comes to cell phones (I'm feel more comfortable on a desktop computer). I was given an old iPhone to replace my even older cell phone, but I need to do a jailbreak to get any kind of app installed.

I tried following the instructions here: http://www.iphonehacks.com/2014/03/jailbreak-ios-6-1-6-redsn0w-p0sixspwn.html. After getting the hang of putting the phone in DFU mode and overcoming USB communication problems every now and then, I finally got to point (20) in the instructions. I saw something in redsn0w about the limerain exploit being installed, but shortly after, I got an error saying "Missing Keys.plist data for this build". Is there anything I can do?

I also tried other instructions I found, but they didn't work for me (p0sixspwn 1.08 doesn't work on MacOS 10.6.8 snow leopard, and 1.07 goes up to 6.1.5 only).

Can someone please help me?