upgrade to the latest Firefox 3.5, featuring improved security, stability, personalization

1.You need to below lines to sources.list file,to do this run below command on terminal

$sudo gedit /etc/apt/sources.list

2.Add below scoure links

deb http://ppa.launchpad.net/ubuntu-mozilla-daily/ppa/ubuntu karmic main
deb-src http://ppa.launchpad.net/ubuntu-mozilla-daily/ppa/ubuntu karmic main

3.Save and close file.

4.Now you need to add trusted key for this repository,by running below line

$sudo apt-key adv –keyserver keyserver.ubuntu.com –recv-keys 247510BE

5.Now you need update apt-get

$sudo apt-get update

6.if you have firefox remove first and run below command

$sudo apt-get install firefox-3.6

All set now,now you can run firfox 3.6