I have an article here that may be able to provide some helpful information for you:
The relevant information for this can be found here:
Joining a network provider's hot spot
To join a network provider's hot spot, you need to set up an account with that provider. The provider typically offers a way for you to sign up immediately, at the hot spot itself. The provider may add variations to this theme, but it goes something like this:
- Choose the provider's network from the AirPort menu, just as you would choose your own AirPort Base Station.
- Open a Web browser, such as Safari.
- The provider automatically pushes a page to your browser, or you enter the address specified in writing at the hot spot.
- The page offers you a form where existing account holders may log in, and it includes a link for new customers to set up an account.
If your experience differs, follow the instructions that you find at the hot spot.
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