Hello cp, welcome to the avast! forum.
Of course you're not stupid, don't be silly

We all have our questions so every now and again and we're here to learn from each other !
For a firewall, you can have a look here:
http://www.kerio.com/kpf_home.htmlYou should read the manual or the faq before you change anything to it's default settings though. Firewalls are necessary but complicated programs. So please do your homework well !
Any questions, just come overhere and ask !
Bye now, Fast.