Syntax: /ns REGISTER password [email]

Registers your nickname in the NickServ database. Once
your nick is registered, you can use the SET and ACCESS
commands to configure your nick's settings as you like
them. Make sure you remember the password you use when
registering - you'll need it to make changes to your nick
later. (Note that case matters! ANOPE, Anope, and
anope are all different passwords!)

Guidelines on choosing passwords:

Passwords should not be easily guessable. For example,
using your real name as a password is a bad idea. Using
your nickname as a password is a much worse idea ;) and,
in fact, NickServ will not allow it. Also, short
passwords are vulnerable to trial-and-error searches, so
you should choose a password at least 5 characters long.
Finally, the space character cannot be used in passwords.

The parameter email is optional and will set the email
for your nick immediately. However, it may be required
on certain networks.
Your privacy is respected; this e-mail won't be given to
any third-party person.

This command also creates a new group for your nickname,
that will allow you to register other nicks later sharing
the same configuration, the same set of memos and the
same channel privileges. For more information on this
feature, type /msg NickServ HELP GROUP.