That title is a bit "the house that Jack built" so let me explain what this is about. Let's say you have a Drupal website and you're using CCK to hold some piece of data or content. Let's also say you want to have a block which takes that CCK field's content and adds it to a link (which could be internal or external). This is one way to do that.
First, ensure your CCK field has been created. You'll also need Views, so install that.
Now create a new View with a block display.
Click on the plus symbol to add a "Field", scroll down to find your CCK field and click Add.