I did a lot of checking and found many how to out there on this one, but having to choose one this one worked great for me and let's hope it does for you also.
I downloaded the files I needed from Ubuntuzilla, it is a self extracting .deb file so pretty straightforward on the installation. Here is where you will find the files from Ubuntuzilla; Sourceforge Ubuntuzilla files, just make sure you get the right one mine is a 64bit so I got the amd64.deb file, if you are running the 32bit you would get the i386.debfile.
After installing from Ubuntuzilla go over to Ubuntu Manual and make sure you have those dependencies enter in terminal command,,
sudo apt-get install libstdc++5 libnotify-bin
I already had those but ran it just to be sure, after this type in command;
and follow the install instructions from there, one other thing when it goes down to getting the key it might take a little while to do so don't get antsy.
"When Firefox starts it probably won't connect to the internet" so in the address navigation type in about:config and hit enter, it will say something about voiding the warranty just continue and in the filter type in network.dns.disableIPv6 you want to double click on that to make it read true instead of false, then close and restart. If you want to read more just go over and read Ubuntuzilla, this worked great for me.