Unless something has changed on 188.8.131.52 untaring it should be all there is to it. Go to the directory where you untared it to and try 'firefox' without the quotes.
I looked at the Mozilla site, and their install instructions might just as well not exist. They are there, but useless.
They geenerally suggest you remove the old version of Firefox. Just delete the directory structure where the old version was.
Java, you will need to create a sym-link to yoru java installation for that to work.
Also, if you had any extensions, you will need to re-install any you can't live without.