right so heres the deal.ive tried setting up xbox live but its not wotrking

we have wireless broadband but the router is in my brothers room.i have a laptop in mine with a dongle type thing in the usb slot for the wireless.i am connecting my xbox to my laptop through the cable that microsoft provided.is this why its not working?
should it be connected to the router directly or should it work going through the wireless laptop thing?
do i just need a wireless adapter?

when i try and click it to get it going it says it runs some tests then says 'IP address=FAILED'...what does this mean?

any help would be great thanks.i just wanna play fifa against some foreign people :(