How to update the version of WordPress you are using??

First of all, I think I have the version 2.2.2 of wordpress. Can anybody tell me where exactly I can see which version I am using? (I started my blog early August this year).
And then, when I have a look at some wp tutorials, their wp-admin area looks different than mine. Less folders etc, and there is a “Settings” button and some more to the right hand side which I don’t have.
So I believe that my version is old.
How can I update to the new version?
Thanks everybody for any help! ??