新手,啥都不会,求帮助

<%@ page import="java.sql.*"%>
<%
 Class.forName("org.postgresql.Driver").newInstance();
 Connection conn=DriverManager.getConnection("jdbc:postgresql://localhost/jasinda","jasinda","jasinda");
%>

以上代码,在原有web目录下正常,自己新建目录下出错.因为原有目录设置了登录才能访问.所以...
出错代码:
exception
javax.servlet.ServletException: org.postgresql.Driver
................

root cause

java.lang.ClassNotFoundException: org.postgresql.Driver