You can find the authorization code (which is also referred to as the EPP code or token) for all your domains by going to 'Domains & Hosting'. As soon as you have clicked on the domain you will see the authorization code at the bottom of the screen under 'Authorization code'.

The following domains use authorization codes: .nl .com .net .org .info .biz .name .ag .cn .in .us .la .pl .sc .tk .tv .tw .mobi and .me. When transferring one of these domains elsewhere you can submit the authorization code to your new provider.

If the information page does not contain an 'Authorization code' field, the domain does not use authorization codes.