Building a document Library

Hi All,

I am wanting to build a site, that can have documents (pdf’s, excel, word etc) uploaded to the site and popped into certain resources, so some can be viewed by all in one location, and others are hidden with-out access.
So... to explain a little better, I am a user with no access but I can download the newest newsletter for the news page, but Bob who has full access can login, view a staff page the search time-sheets, and download a timesheet pdf.

Can this be done with Modx, and any guidance would be great...