Facetime Settings Changed on Macbook Pro

Hi everyone, I need help to change email settings for facetime on my macbook pro.. First Mac and I want to be able to connect my Ipod touch 4th gen with my macbook through facetime, but i might have entered same account info in both devices, so I am trying to change email in facetime settings on the macbook, but haven't been able to figure out how.. HELP.. Thank you so much.