[Samba] samba problem

[helpdesk]

Hello I am kinda new to the whole samba and linux platform.  Well I have a
samba problem.  We are using Red Hat 7.3 as our intranet server and we are
trying to use samba for rights and security.  We want to lock everyone
except IT department from accessing files on the intranet server.  As of now
everyone can get into it.  We are trying for a password protected area.
Also if we change the security level from share level to anything else, it
will not let anyone in, or it will ask for a user name and password that we
have no clue which it is.  Can anyone help?  Thank you.