If you have a password protected wireless system, then you have to provide a guest with the network password. As for your computer a Guest account is already pre-configured in OS X. Users can log into the Guest account without any password but have very limited access.
Thanks for the answer.
Does this mean that I will have to give the password for the network to any guest coming at home with their own computer and iPad? I can't offer them a limited access to the network (internet and printers)?
How do you know which generation is your TC aor airport extreme or express.
Thanks in advance.
Your network is not part of your computer's account. When you configure security for your network and assign a password that's it. The router does not accommodate multiple passworded accounts. If I have a wireless equipped computer and know the password for your network then I can access it as long as I am in range of your router.
You can, of course, change the password in the router's configuration while your guests are present if you are concerned.
I'm not sure about telling the generations, but you can find spec sheets at support.apple.com/specs/. They may help you identify the differences. Most likely there's an easier way but I don't know it.
To find the which generation airport (exp or ext) go to application/utilities and open aiport.app The first "screen" you see in the app before clicking anything has the generation number.
Sounds like you figured out that you _can_ create a guest account for the wireless from the link Kappy provided.