denying group of users from r/w/x files

[Ali Hamad <ali hamad34 gmail com>]

Hello :

I really do not know how to do this, but I really need it.  Here is what 
I want to do :

remove all the Selinux rules ( targeted ) since I really do not need 
them. I only need selinux to do only the following :

   a)  create a rule for file that can not be accessed from known group 
of users. i.e group A can not read/write/execute this file.  However, 
the file permission is 666 and that file permission can not be changed.
   b)  directory that has permission of 777. However, group A of users 
can not write/read/execute  it.

Here is what I came up with :
/usr/sbin/semanage fcontext -a -t ?? /var/file.txt

I did not know what type I should put in there.

would you please guide me how to achieve my goal ?

Any suggestion is highly appreciated.

Ali.