Displaying Entry posts From One Type of Catagory

Hello,
I’m replacing a Movable Type installation with WordPress. In my old blogging software, movable type, the application created a static page that only listed posts from a catagory named “DER News” that I pulled into my main index page using a PHP include. The aggregate of all of the category entries, like normal, are then displayed in a seperate directory on another index page. I was thus able to seperate one index pages by catagory and the other index page had all the entries from every catagory.
I’ve seem to run into a problem: I don’t know how to use the PHP tagging system to display posts from only one type of catagory. Is this possible? If so, what would the code look like?
Thank you for your help.