How do you transfer all the nice little Firefox settings, bookmarks, plugins and addons that you already have on your old computer to your new one? I’m sure there must be some configuration file somewhere in your program files or the code of firefox itself, but for use not so fluent with firefox, we can use 3rd party tools.

Firefox Extension Backup Extension (FEBE)

FEBE allows you to quickly and easily backup your Firefox extensions. In
fact, it goes beyond just backing up — It will actually rebuild your
extensions individually into installable .xpi files. Now you can easily
synchronize your office and home browsers.
FEBE backs up your extensions, themes, and (optionally) your bookmarks,
preferences, passwords, cookies and just about everything else Firefox
offers (it can even backup/restore your entire profile).

Backups can be performed on demand or scheduled for daily, weekly, or
monthly unattended runs.

mozilla addons url:https://addons.mozilla.org/en-US/firefox/addon/2109

MozBackup

MozBackup is a simple utility for creating backups of Mozilla
Firefox,
Mozilla Thunderbird, SeaMonkey, Mozilla Suite and Netscape profiles.
*It allows you to backup and restore* bookmarks, mail, contacts, history,
extensions, cache etc. It’s an easy way to do Firefox backup, Thunderbird
backup .

the homepage url:http://mozbackup.jasnapaka.com/