NAT+IPFW

[Jer]

Dear all

I need to do the following

I have a fbsd router that runs nat and routes some public IP addresses

I ned to use the ipfw rules to deny traffic from the public IP's AND the 
nat o do bandwidth limiting

eg
deny tcp from 192.168.200.1 to www.yahoo.com http out
and
deny tcp from 24.199.213.1 to www.yahoo.com http out

my questions are where do I place the rules in relation to the divert rules etc

Thanks