okey well since ur on this im assuming u got internet

Either for wireless internet you need to buy a wireless router (expensive, but it means u got internet all over ur house so its gd when using more than one comp or a laptop)
Wii has a built in wireless so if u got this it can be done within 1 minute.
If you do not have wireless i think (not 100% sure cuz i do have it) u should go to a hardware store and see if they sell a wii LAN adapter, this will work the same way as your computer. It will have one usb port, which goes into you wii, and one LAN port which u will connect the same cable that goes into your computer to.
Hope this helped

have fun gaming