1- Simply go to Firefox homepage(here) to download the package from origin provider.
– The package is with extension “.tar.bz2″
2- Make sure the package is located on your home folder
3- Open Terminal/Konsole and run “su”command then type your password if asking to use wide installation
4- Move firefox package to /usr/local/bin using this command:
#mv firefox-3.6.9.tar.bz2 /usr/local/bin