-So firstly let me explain the relationship between content spots, rules and resource collections. The minimum you would need to implement you're use case.
Content spots invoke a rule and return results. They have a default rule mapping, but you can set the desired rule on ContentSpot from your portlet that you want to invoke.
Rules use attributes etc and return results from a Resource Collection(Web Content is an OOB Resource colllection, so this part is easy).
Resource Collection is used to access data that can be queried from the rules. Ex: Web Content, databases etc
So you'll start by creating some WCM content let's say a bunch of news articles. You will define some PZN rules to conditionally select these content items let's say based on created date or any condition. You will then create a content spot and set this rule as a default rule on ContentSpot. Then just call the content spot from you're jsp code.
-I havent used WCM taglibs extensively but if you know how to pull content using WCM tags, you can create "PZN WCM component" to call a PZN rule(which inturn could be returning the web content) and call that PZN wcm component from wcm tags.