Mcafee Firewall

Hi,

I have a small peer to peer network.
Computer A directly connect to network which has firewall installed.
Computer B connect to internet through computer A.
If I tick the "Mcafee firewall network filter" in the internet connection,
which means Mcafee will filter the internet connection, then computer B
cannot access the internet. I have to untick the filter in order to allow
compter B to access the internet, but this means the Mcafee has no effect.
How can I enable the Mcafee firewall while computer B still can access the
internet?

Kind regards
Adrian