i used this in my school cuz they just got new macs and now i get wifi in more places in the school

1. go on the mac and open settings.
2. go to sharing.
3. click on the internet sharing on the sidebar.
4. change the settings for the mac your using. for me i chose to share my ethernet through airport.
5. then check the box next to internet sharing on the sidebar and it should work.
6. go to your ipod/iphone and connect!

enjoy