To find your version, in the Help menu select "About Firefox", that will also check for updates.

For info you are using Firefox 4.0, the latest version is 4.0.1

thank you for the reply.. that was quite useful.. then can you something about mozilla aurora?

Mozilla have recently changed over to a rapid release system similar to what Google does with Chrome. As part of that they have introduced several update channels. The Aurora channel is intended for those who want to test development versions of what will become the next major update for Firefox. For a bit more information see http://blog.mozilla.com/blog/2011/04/13/new-channels-for-firefox-rapid-releases/

You can get the Aurora build from http://www.mozilla.com/en-US/firefox/channel/

actually what is my doubt is... is aurora a web browser? whats its use? im weak in this part...

Aurora is a web browser, it is a development version of Firefox. It is used for those who want to test the features and innovations that are intended to be in the next version of Firefox.

The development builds are not intended for most people, only for those who are happy with testing programs.

Thank you so much... I am clear now...