Connect my iPHONE to a desktop to access internet

Hi Folks,
My office blocks me from accessing YouTube and others and none of the proxies work. So i want to disable my Lan and connect my iPHONE 5 with iOS 7.0 to my desktop with a USB wire and share my iPHONE 3G internet with my Desktop.
How can i do this. Can anyone give me all steps please.
I have a Windows 7 OS desktop
Thanks
