I'm new to Ubuntu and while browsing over forums I saw goto System > Administration and so on. So I wanna know how I can actually goto System, means where can I find System then Administration and so on?
Click on the home/start button of your keyboard or on the icon on the side called as "dash home". It will present you with what is called as dash. It is like a search option. Type what ever you want to search in your system here. In your case type "System" in the search bar. It will show you all the applications documents etc having a word "system" in them. Select the required application and there you go.
PS : This solution works only you are in Unity. Not in a fallback/old version of gnome shell that is available through gnome-panel for 11.04 and above.
As of 12.10: see the Additional Drivers tab in the Software Sources menu.
In case of AMD you will see different drivers here.
You can get there from the normal places like Ubuntu Software Center (it is in the options at the top left)