This is pretty simple to do. This is covered in the 2nd tutorial so you might want to read that http://doc.silverstripe.com/doku.php?id=tutorial:2-extending-a-basic-site . Basically you need to do 2 things. I am going to assume you have your holder/news page types the same as Tutorial 2.
So step 1 Make the function that gets the latest news. Add this to the class Page_controller in Page.php.