Installation of Mozilla thunderbird mail client in Linux:

Download Thunderbird from http://www.mozillamessaging.com/en-US/thunderbird/ to your Linux desktop

Let us say you would like to install thunderbird in your own home directory called /home/rad/

Copy your downloaded file to /home/rad/ and untar it:
$ cp /home/tom/Desktop/thunderbird-2.0.0.0.tar.gz .
$ tar -zxvf thunderbird-2.0.0.0.tar.gz
Now software was installed. To start Thunderbird mail client, enter:
$ cd thunderbird
$ ./thunderbird

To create thunderbird icon on desktop.

Right click on your Linux desktop
Select Create Launcher
Fill the details as follows:
* Set name to : Thunderbird
* Set command to : browse "thunderbird" inside the directory Thunderbird.
* Set comment to : My Email Client
* Hit OK to create an ICON