There are so many ways to do this and this is the easiest one.
Step 1: The Easy Part
Hit the start menu button and go to connect to and click on show all connections.
Step 2: The Harder Part
Now that you have the window up. Right click on the wireless network connection and go down to properties.
Step 3: The Easiest Part Click a Button.
Go to the Advanced tab. Click on the Allow other network users to connect to the internet through this computer. I think that is close to what it says. I am not for sure though. And that is it. Just plug one end of an ethernet chord into the computer and the other into the Xbox. If the computer says that there is a problem, right click on the wirded network toolbar and repair. That should take care of it. HAVE FUN GAMING
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Look the Syndicate up at xiledgaming.com