This question seems to appear every so often,
in a few different forums, not just this one Installation Forum,
and not just in the forums of this Sun web site.
Use the Forum search, using keyword "useradd" to see earlier posts.
You log in as the root user, and then you use the useradd command.
That will permit you, as the system administrator ( the "root" user )
to create accounts for whichever other users you would want to be able to use this system.
If you need assistance with command syntax, there are man pages that you
can invoke to see on your screen.You would do ...
# man useradd <enter>
When you have successfully created the new user(s),
you can exit out as root and then log in as that user with its associated password.