Internet explorer proxy problem

Hi i'm new here and well when i try to use internet explorer it says internet explorer cannot display page i diagnose the problem and it says my.yahoo.com is not set up to establish connection on port "world wide web service (HTTP)" with this computer. it wants me to change the proxy server and port or something like that from my understanding...i am good with computers but i don't know anything about networking help would be greatly appreciated.
p.s. i just had one of those problems where i got Antivirus System PRO but i removed it could that be it?

Hello,

Please start Internet Explorer, and when the program is open, click on the Tools menu and then select Internet Options.

• Now click on the Connections tab and then the Lan Settings button
  
• Under the Proxy Server section, please uncheck the checkbox labeled Use a proxy server for your LAN. Then press the OK button to close this screen. Then press the Apply button and then the OK button to close the Internet Options screen. Now that you have disabled the proxy server you will be able to browse the web again with Internet Explorer.