Where is your class? if its in the same directory then it should work, PHP looks first at where you say your script is , oin your case the same directory & if it can not find it there it looks in your include path (which you really would not be using on a shared host)
but are you getting an error from the include() ?
require('script.php');echo "script.php has been found";
if your page does not die at that line then your class has been included but there is an error within it which is why you get undefined function warnings
MVC is the current buzz in web application architectures. It comes from event-driven desktop application design and doesn't fit into web application design very well. But luckily nobody really knows what MVC means, so we can call our presentation layer separation mechanism MVC and move on. (Rasmus Lerdorf)