How to start on modifying the admin portion of Magento

I need to modify the Magento admin system to allow authenticated users to find products via manufacturer and category.

So, basically, either two select elements which an option for each manufacturer/category, or two autocomplete boxes.

What I need help with is how to get started. I can guess I edit the views to add the controls (which I've figured out how to do), but then where would I add th开发者_开发知识库e code to allow this functionality? Do I modify queries or modify how the model gets the products?