Recent changes per category

Hello WordPress masters,

I’m completely new to wordpress so I guess you will be redirecting me to the wordpress for dummies pages but i’m going to try it anyways.

I want to make a page in wordpress that shows recent changes of a certain category only.

So what I did:

I installed the plugins “Recent Posts Widget Extended” and “Post Tags and Categories for Pages”.

So with the “categories” plugin I add a page to a category. Next with the “Recent post” plugin I say “cat<the category name>” but nothing is shown after.

I hop esomeone is willing to help me out here. Thsi is the most important feature of our word press site.

Thanks!