Where is the firewall situated at on the computer?

Yes its me again lol. thx to e1 4 the answers but still got trouble. i phoned up a computer shop and they told me to bring the comp in to do a memory test but its gonna cost me. i was told it could be my firewall
Answer
Control panel and security centre find it in there. you can turn it on or off in there. you can also in exceptions (i think) tell the firewall to allow access to the programmes or website that you require. hope this helps