Group Permisions 101 Needed

["Waldher, Travis R" <Travis R Waldher boeing com>]

I'm pretty new to Unix, and I have not dealt with NIS usernames and group permissions on a seperate server that is a NIS client.  So, I have some very basic questions I hope people here will be willing to answer.

If I am a NIS user called Travis and I log in to a server called dataserver.  I have a group folder called mygroup.

How do I restrict other NIS users who are not in that group from getting in?  I know the chown, and give it a groupname, we will call it "mygroup" as well for this discussion.

Do I have to have a /etc/group file, assign a GID.  Then on the NIS server assign the user to that same GID?  

I don't need a oversimplified step by step but general steps and which files I need to modify would be greatly appreciated.

Thanks,
Travis