I got a xbox 360 live for xmas i need the xbox to conect throught the pc to the rotore but it want. any hlp?

i got a xbox for xmas and live. i want to Connect my xbox to the internet through my pc then the rooter and after that the modem. however i have failed to do this every time. can some one plz right me a step by step giuld on how i can do this. thankyou for your help.