How do I register a Sling Servlet?

Hi,

I am tring to create a servlet for my web application.

I have tried to follow the tutorial at: http://blogs.adobe.com/aaa/2012/09/cq-tips-and-tricks-1-how-to-define- a-slingservlet-cq5-5-5-6.html

And when I try to access the resource,  I kept getting an 404 page.

Does anyone know how to resolve it?

Thanks