Need help setting up a Redhat 6.1 Firewall and DHCP server

["John P." <johnp () industrynet net>]

I am getting a cable modem in less than 2 weeks and I would like to setup a linux box as a firewall and a DHCP server.  
A friend of mine has one setup so I know it is possible.  But he had a friend of his set it up for him.  I would much 
rather set it up myself so I can learn linux at the same time.  I know the VERY basics of linux.  I have read the 
firewall howto.  But about half way through I get confused because I'm not sure exactly what changing those settings is 
doing.

I want a basic DHCP server.  And I want the firewall to block all incoming traffic (not exactly all, but you know what 
I mean..=).  I don't need or want it to block any outgoing traffic.  If possible I'd like to make it so if somebody 
tries to get it, a reply isn't even sent that the port exists, where the computer just ignores the request.  I know all 
the hardware I need, so I'm set on the hardware side.  Just the software side I'm having trouble with.  If anybody 
could please help me out, or point me to a howto that explains in laymens terms how to set this all up.  any help is 
GREATLY appreciated..thanks

John