Seems a bit off topic for the site, but oh well. I'm not quite sure what you mean by "go straight to the directory"... I'm assuming you don't want a directory listing to be allowed. Since this is in reference to maleteen2000's question, I'm guessing you're refering to file system permissions rather than web permissions (though "Forbidden" sounds more like a httpd error than an OS error). If that's so, I don't think you can do that (i.e. prevent directory listings while allowing file access), at least not according to a quick test I did on Solaris. But I don't know why you would want to, either... you'll hear quite often that security through obscurity isn't security at all. Can you be more specific about what you want to do?

As for what the three concerned parties are (u, g, o), do an 'ls -l' in a directory to see all the file permissions and owner and group settings. Each file has an owner (you, if you created the file), and a group. When trying to access a file, the OS first checks to see whether you're the owner of the file; if so, owner (u) permissions apply. If not, it checks to see whether you're a member of the group to which the file belongs; if so, group (g) permissions apply. If neither of these is true, other users' (o) permissions apply. Unless you've explicitly set up groups so that the group is trusted somehow more than others, you'll probably want to set the permissions for group and others the same (almost always without write, read and execute depend on what you want).