If you are using 12.04 ie Precise Pangolin, and want to upgrade to Canonical’s latest release, ie, Ubuntu 12.10 Quantal Quetzal then its just a matter of following a few steps!
Primary thing while updating any system is to ensure that the data is safe. So you can either install it via Bootable Pen Drive by downloading the tar file from here and use Linux Live ( Lili ) or UnetBootin and reboot! ( Dont forget to change the boot order! )
You may also do it via Terminal.
Just do this:
sudo apt-get update
Click on “Check for updates” . You may or may not install all updates, but on the top corner, you can see that there is an option to update the distribution.
If you can not see that option, go to Software Sources -> Updates.
In that “Notify me for a Canonical upgrade” Select : “Any distribution”
Now open the update manager again, and click upgrade on the top.
Enjoy Quantal Quetzal!
P.S.: In a matter of two weeks time, BITS Goa will witness Waves! Arguably one of the biggest cultural fests!