Buddy,

In Unix, the users have been characterised into three groups:
Owner (you)
Group (a group of other users that you set up)
World (anyone else browsing around on the file system)

So you can put the users according to your conditions. Once this is done then u can provide permissions to those groups as a whole which will equally be applied on the users inside it.

This is the only way. We can't give permissions to users individually.