IPTables and Port Forwarding?

$hy_guy asks: "I have been totally striking out finding some info on how to do port forwarding in Linux. I am currently running Mandrake 8.1 as my router and i would like to forward a particular port to another machine on my LAN. I'm pretty sure I have to use iptables but I have been very unsuccesful at the proper syntax. I have scoured through Google and I have not really found any useful info. I would appreciate just a link or something to point me the correct direction. Thanks for the help" I know many of you may think this is an FAQ, but it seems that IPTables confuses many people as this is not the first time this question has hit the bin. If someone has a good general reference on the use of IPTables, please share.