switching users on my computer

[nirvana]

hello.
i cannot seem to be able to log off of my user to
the log out screen so other members of my family could go
to their accounts/user. i press the log off key and
nothing happens. the computer logs me off automatically
when the screensaver comes on after a certain period of
time. i don't know where to find help. so if someone
knows please mail me back and let me know. your help is
greatly appreciated.

thank you,
Nirvana.