My friend just told me, That i could have more than one desktops in Ubuntu and then choose which one to use when the Ubuntu starts up and goes to login screen. I have Ubuntu 12.10 and i think my default desktop is unity, so can i have gnome desktop and more desktops? And if so, How and where to install them and how to use them?
yes thats what said in that link .
so as you asked , if you want to install gnome-shell
open your terminal and type as
I like KDE , to get it you can do
IF you want some light desktops