tomcat中的初级问题！各位来指导指导

还有就是我写了一个servlet，把class文件放到了classes目录下，再次启动tomcat时，还是找不到servlet阿，跟上面的错误是一样的，我的代码分别如下，肯请各位指点一二，我是刚学的
web.xml
<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
    "http://java.sun.com/dtd/web-app_2_3.dtd"><web-app>
  <display-name>Welcome to Tomcat</display-name>
  <description>
     Welcome to Tomcat
  </description>
    <servlet>
        <servlet-name>HelloWorld</servlet-name>
        <servlet-class>HelloWorld</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>HelloWorldWWW</servlet-name>
        <servlet-class>HelloWorldWWW</servlet-class>
    </servlet>
</web-app>servletimport java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;public class HelloWorldWWW extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws IOException, ServletException
    {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<html>");
        out.println("<body>");
        out.println("<head>");
        out.println("<title>Hello World!</title>");
        out.println("</head>");
        out.println("<body>");
        out.println("<h1>Hello World!</h1>");
        out.println("</body>");
        out.println("</html>");
    }
}
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;/**
 * <p>Title: </p>
 * <p>Description: 我的第一个servlet程序</p>
 * <p>Copyright: Copyright (c) 2003</p>
 * <p>Company: owner</p>
 * @author L.M.X
 * @version 1.0
 */public class HelloWorld extends HttpServlet{
  public void doGet(HttpServletRequest request,HttpServletResponse response)
      throws ServletException,IOException{
    PrintWriter out=response.getWriter();
    out.println("Hello World");
  }
}