How to connect to xbox live through a macbook air?

[IUcookie]

Ok I've been having issues with this. I bought an ethernet/usb adapter from Apple today because the Macbook Air doesn't have an ethernet port. Now after I plugged everything in, what do I have to do? I should add that I am connected to the school's wifi on my Mac so thats not an issue. I've googled and everything and I've tried sharing the network but it doesn't follow what I'm seeing.

I would really appreciate help if you can give any. I've had issues with this for a while now!

 

[IUcookie]

UPDATE: I am connected but it says I will have limited access. It stated that the NAT was on moderate, so thats why i'll have limited access. Any way to resolve this?

Once again I would really appreciate it!

 

[Luigi3]

Nat is moderate when you have unopened ports in your network/router.