Help me with iptables. About CoyoteLinux

Help me with iptables. For more information about CoyoteLinux-Linux Enterprise Application-Linux server application, see the following. You Want To Set firewall rules on the route so that computers in the LAN can only access websites with the specified domain name on the Internet, and nothing else can be accessed, including network applications such as qq. But I don't know how to write it in the firewall configuration file in Coyote Linux. Please help me. The following is the default content in the firewall configuration file. Thank you very much for your explanation.
#! /Bin/sh
#
# Local Custom Firewall rules

# Level 7 Filtering example rules:
# Block Kazaa, Morpheus, iMesh, Grokster, eDonkey, eMule, DC ++, etc:
# Iptables-t mangle-a postrouting-m layer7 -- l7proto fasttrack-j DROP
# Iptables-t mangle-a postrouting-m layer7 -- l7proto edonkey-j DROP
# Iptables-t mangle-a postrouting-m layer7 -- l7proto directconnect-j DROP

# Other Examples:
# Iptables-t mangle-a postrouting-m layer7 -- l7proto ftp-j LOG
# Iptables-t mangle-a postrouting-m layer7 -- l7proto pop3-j MARK -- set-mark 1
#
# To see a list of all available protocols use this command:
# L7-protocols/ls/etc/


# Attention: To enable the commands below can cause some side effects
# Syn-flood and DOS protection
# Iptables-a forward-p tcp -- syn-m limit -- limit 1/s-j ACCEPT
# Port Scanners protection
# Iptables-a forward-p tcp -- tcp-flags SYN, ACK, FIN, RST-m limit -- limit 1/s-j ACCEPT
# Iptables-a forward-p tcp -- tcp-flags all syn, ACK-j DROP
# Ping-of-dead protection
# Iptables-a forward-p icmp -- icmp-type echo-request-m limit -- limit 1/s-j ACCEPT
# IP Spoofing protection
# Iptables-a input-s 10.0.0.0/8-I $ IF_INET-j DROP
# Iptables-a input-s 172.16.0.0/16-I $ IF_INET-j DROP
# Iptables-a input-s 192.168.0.0/24-I $ IF_INET-j DROP