请问如何配置WEB.XML？听说SCWCD中考了不少，急~~~~

<?xml version="1.0" encoding="UTF-8" ?> 
- <!--  edited with XML Spy v3.5 NT (http://www.xmlspy.com) by  () 
  --> 
  <!DOCTYPE web-app (View Source for full doctype...)> 
- <web-app>
  <display-name>SCWCD</display-name> 
  <description>学习配置DD</description> 
- <context-param>
  <param-name>user</param-name> 
  <param-value>scwd</param-value> 
  </context-param>
- <context-param>
  <param-name>password</param-name> 
  <param-value>scwcd</param-value> 
  </context-param>
- <listener>
  <listener-class>javax.servlet.http.HttpSessionListener</listener-class> 
  </listener>
- <servlet>
  <servlet-name>index</servlet-name> 
  <servlet-class>servlets.index</servlet-class> 
- <init-param>
  <param-name>name</param-name> 
  <param-value>servlet</param-value> 
  </init-param>
- <init-param>
  <param-name>password</param-name> 
  <param-value>scwcd</param-value> 
  </init-param>
- <security-role-ref>
  <role-name>my</role-name> 
  </security-role-ref>
  </servlet>
- <servlet-mapping>
  <servlet-name>index</servlet-name> 
  <url-pattern>/index</url-pattern> 
  </servlet-mapping>
- <session-config>
  <session-timeout>30</session-timeout> 
  </session-config>
- <mime-mapping>
  <extension>html</extension> 
  <mime-type>text/html</mime-type> 
  </mime-mapping>
- <mime-mapping>
  <extension>doc</extension> 
  <mime-type>application/msword</mime-type> 
  </mime-mapping>
- <welcome-file-list>
  <welcome-file>index.html</welcome-file> 
  <welcome-file>index.jsp</welcome-file> 
  <welcome-file>index.htm</welcome-file> 
  </welcome-file-list>
- <error-page>
  <error-code>404</error-code> 
  <location>error/404.html</location> 
  </error-page>
- <error-page>
  <exception-type>java.lang.Exception</exception-type> 
  <location>error/exception.html</location> 
  </error-page>
- <taglib>
  <taglib-uri>/mytld</taglib-uri> 
  <taglib-location>/WEB-INF/tlds/mytld/tld</taglib-location> 
  </taglib>
- <security-constraint>
- <web-resource-collection>
  <web-resource-name>my</web-resource-name> 
  <url-pattern>/index</url-pattern> 
  <url-pattern>/admin/*</url-pattern> 
  <http-method>get</http-method> 
  </web-resource-collection>
- <auth-constraint>
  <description>Secury Test</description> 
  <role-name>Admin</role-name> 
  </auth-constraint>
- <user-data-constraint>
  <transport-guarantee>NONE</transport-guarantee> 
  </user-data-constraint>
  </security-constraint>
- <login-config>
  <auth-method>FORM</auth-method> 
  <realm-name>Form Based Scuruty</realm-name> 
- <form-login-config>
  <form-login-page>/login.html</form-login-page> 
  <form-error-page>/error.html</form-error-page> 
  </form-login-config>
  </login-config>
- <security-role>
  <role-name>my</role-name> 
  <description>这是一个安全规则</description> 
  </security-role>
  </web-app>