CMS Filtering out articles based on category

[محروم.كوم]

I'm in the process of writing a plugin to filter out just the articles assigned a certain category and only show those articles in each section and I really cant wrap my head around the new extremely object oriented system. In vB3 I could just write an addition to the WHERE syntax in a variable and hook the plugin into the right hook, but now I'm not really sure how to acomplish the same thing... __DEFINE_LIKE_SHARE__