Renu, Eclipse is an IDE. You need a server to get a servlet container. Free ones are Tomcat or JBoss. You can optionally install a plugin to integrate Eclipse with the server.
Check the sites below based on the Servlet Container you are using. I followed the steps in these sites and integrated my Eclipse with both JBOSS and Tomcat.
If not, you may be trying to "run before you can walk". Try searching the web for "eclipse tutorial" and following the steps in any tutorial you like. Make sure you have got used to the basic steps of creating projects, compiling, testing and running stand-alone code. Once you understand at that level, then you can look into using some of the many tools to run your code in an application container.