Create or find a registration system... phpbb works for this, and would also give you a forum to play with... but any registration system you can understand will do.
Find out how the registration system stores it's username variable, and use it to set the parameter "nick" to that username variable. For example, if it was stored by using sessions, under the variable name "uname", it would look something like this: $params["nick"] = $_SESSION['uname'];
Also make sure to prevent users with no uname from enterting.
Set the frozen nick parameter to true, which will prevent them from changing nick names.
Finally, use your registration system to prevent multiple registrations from the same IP.
If you have any other questions, feel free to post them.
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