/mode This lets you determine who can join a channel you've created.
/mode #channel +s
creates a secret channel.
/mode #channel +p
makes the channel private
/nick This lets you change the name by which others see you.
/nick fleepo
would change your name for the present session to fleepo. People can still use /whois to find your e-mail address. If you try to enter a channel where somebody else is already using that nickname, IRC will ask you to select another name.
/query This sets up a private conversation between you and another IRC user. To do this, type
/query nickname