How to do change language on mac?

I have an imac



and I type in italian to english.



How do you change from italian to english keyboard or english to italian (if its different),,,



my friend changes it by using command and space.



But, my mac doesn't do that...How to do change language on mac?
http://tinyurl.com/y9yr3suHow to do change language on mac?
You can change the shortcut key to command + space if you want at `System Preferences` -%26gt; `International`



Or if you want to use some other shortcut key, that's fine too.