About modify mac os x version number problem

To modify modify mac os x version number, I follow the online tutorial:
First, open the console;
Second, using the root user;
Command: sudo-s
After entering the password
Third, edit / System / Library / CoreServices / SystemVersion.plist file

In the third step I enter "more / System / Library / CoreServices / SystemVersion.plist"
Then the question came, xml code is displayed, but can only view can not be edited.
I ask how can I do?
Reply:
After editing a plist file to replace restart
Reply:

cited a floor ybh37 reply:

After editing a plist file replacement

restart

I used finder to find, but could not find. Only found:
[Img = C: \ Documents and Settings \ Administrator \ Desktop \ 1] [/ img]
But these two are unrelated content.
Reply:
Picture not made up, because it is something like two pages, one is called "Search | Health, Beauty, ... Magezine", one called "Can not open the page."
Reply:
vi / System / Library / CoreServices / SystemVersion.plist