How to change the user name and password in CUPS?

[James Ng Yuen Sum <james_nghk_debian_user@yahoo.com.hk>]

Hi,

I am a newbie in CUPS. When I first install CUPS with .tar.bz2 file, I
choose the user name and password same as the root.

I have a problem with I print the test page, which cannot be printed,
and the state always is "aborted", therefore, i take the question in the
newsgroup in my city's linux community, one helper have the experience
same as me, and he solve it when the user name and password is not that
of root, so I want to ask how to change the user name and password.

Regards,
James Ng