Every servlet is specified in web.xml file. Like
<servlet>
<servlet-name>Anyservlet</servlet-name>
<servlet-class>com.yourpackage.AnyServlet</servlet-class>
</servlet>
You have to put your web application in the webapps folder of the TOMCAT. suppose you make a floder MySite in the webapps folder of the TOMCAT. now for calling a servlet you must give address as
http://localhost:8080/MySite/Anyservlet