I suspect that you havn't included your new servelts details in the web.xml document which I belive is in your web-inf directory.
The way tomcat works in regards to servlets is that you have to place the servlet information in the web.xml document so it knows when to load that information.
<servlet>
<servlet-name>org.apache.jsp.index_jsp</servlet-name>
<servlet-class>org.apache.jsp.index_jsp</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>org.apache.jsp.index_jsp</servlet-name>
<url-pattern>/index.jsp</url-pattern>
</servlet-mapping>
The url-pattern tells tomcat that if someone goes to
www.yourdomain.com/index.jsp to load this serverlet.