problems to display specific category posts with archive.php

Hi everyone,

I have a private section on a site, when a client comes and look for his daily information, need to login to access it, but now I need to display in the sidebar an archive section, and that’s ok, but if I click on, for example, the link with the archive of april, the loop show me all the posts of all the clients, and that’s one thing I don’t want to happen.

How can I custom the archive.php to display just one category, and not all?? when I click on the links in the sidebar

I hope you can help

Thanks!!!