Please help me guys please i sold ps3

Please help me i am helpless for weeks

I have a modem and in the modem there is a router so with that modem i can browse on the internet with my iphone or cellphone or anything

but when i connect my xbox 360 it won't

my modem/router is upstairs and xbox 360 down so the live cable isnt usefull

Please help me its been 2 months

do you have a NEW xbox360 with wireless built in OR an older one without? you probably need this

http://www.xbox.com/en-US/hardware/x/xbox360wirelessnnetadapter/