Incomming connections

[D Medina]

I am trying to set up a 4 computer wireless network. All
th computers can see each other and 2 of the 4 are
available for sharing files. I would like to limit the
access to only thata computer, and thought the incoming
connections would be the area to do it. Problem is I
can't find incoming connections anywhere. Help say to
look at Network Connections, but I see nothing. Can
anybody help.