Setting up of private directories

Hi All,

I apoligise in advance if what I am asking is trivial or covered in some 
documentation ( by the way a source of code wu-ftpd documentation would be 
appreciated, is there a good HOW_TO doc somewhere ?)

Anyway I wish to setup up two private directories, say X and Y, i want a user Y 
to be able to access and upload to dir Y, but not be able to access or list dir 
X, and vice versa.

What is the most preferable and secure way of achieving this ?

The system is running Solaris 2.4 for X86.

Thanks in advance

Michael Clarkson