querying

I have a Drupal 7 question that I can't seem to find a clear solution. I have a lot of pdf files that I want to add to our website. I want to be able to query/filter the pdf files based on year and department. I would want something like a drop down menu or radio buttons to accomplish this so the user can select to sort by year and/or department. I can't figure out how to add any taxonomy or association to the file to do so.

Do you know if this can be done or not? If you know of any books or tutorials that will help me, I would greatly appreciate any assistance.