So it will be better if you tell me from the scratch if possible for you.
That's a lengthy topic that can't be explained in a forum like this. Work through the tutorial Kiran linked to; it's very extensive.
Also, don't use NetBeans. It has a learning curve all its own, and trying to use it will distract you from learning Tomcat and servlets. You can always start using an IDE once you've mastered the basics.