APACHE中如何在同一个IP配置两个虚拟主机

这是一个例子:
NameVirtualHost 192.100.100.1
ServerAdmin njzadmin@sina.com
DocumentRoot /wwwroot
ServerName www.a.com
ErrorLog logs/a.com-error_log
Customlog logs/a-access_log common
ServerAdmin sonymusic@china.com
DocumentRoot /wwwroot2
ServerName www.b.com
ErrorLog logs/b.com-error_log
CustomLog logs/b.com-access_log common

补充：Php教程,Php入门